pkl-core: Migrate nullness to JSpecify (#1601)

Replace pkl-core's local nullness annotations with JSpecify annotations. Enable NullAway checking for pkl-core packages except org.pkl.core.ast and org.pkl.core.stdlib. Notable code changes: - Add a dedicated late-init constructor to VmTyped - Move VmExceptionBuilder's fallback message derivation from withCause() to build() - Split VmException rendering between builder-provided messages and string-backed messages - Initialize MessageTransport handlers with default throwing handlers - Update JSON helper collection types to allow nullable values JSON arrays and objects can contain JSON null, so the Java Map/List element types need to model nullable elements explicitly - Make public command transform APIs accept nullable transformed values Command transforms can produce null for optional/default handling, so the BiFunction and options-map element types now model that explicitly - Make ExecutorSpiException accept nullable message and cause Existing call sites can pass nullable causes from Throwable.getCause() - Remove JSR-305 semantics from `@LateInit` JSpecify does not support the same type-qualifier-nickname pattern, so `@LateInit` is now documentation plus a NullAway constructor-initialization exemption Out of scope: - NullAway checking of org.pkl.core.ast and org.pkl.core.stdlib - IntelliJ warnings related to `@LateInit` fields - Removing the JSR-305 dependency, since concurrency annotations are still in use
2026-05-25 08:09:17 +02:00 · 2026-05-21 22:57:20 +02:00
parent 63ef60f3c4
commit 3dc93cbd4a
261 changed files with 709 additions and 723 deletions
@@ -13,6 +13,8 @@
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
+import net.ltgt.gradle.errorprone.errorprone
+import net.ltgt.gradle.nullaway.nullaway
 import org.apache.tools.ant.filters.ReplaceTokens

 plugins {
@@ -21,6 +23,7 @@ plugins {
  id("pklJavaLibrary")
  id("pklPublishLibrary")
  id("pklNativeLifecycle")
+  id("pklJSpecify")
  idea
 }

@@ -57,6 +60,7 @@ dependencies {

  add("generatorImplementation", libs.javaPoet)
  add("generatorImplementation", libs.truffleApi)
+  add("generatorImplementation", libs.jspecify)

  javaExecutableConfiguration(project(":pkl-cli", "javaExecutable"))
 }
@@ -107,6 +111,18 @@ tasks.processResources {

 tasks.compileJava { options.generatedSourceOutputDirectory.set(file("generated/truffle")) }

+tasks.withType<JavaCompile>().configureEach {
+  options.errorprone.nullaway {
+    // Do not require LateInit fields to be initialized at construction time.
+    // Unfortunately, IntelliJ doesn't currently understand this,
+    // and therefore emits many warnings related to LateInit.
+    excludedFieldAnnotations.add("org.pkl.core.util.LateInit")
+
+    // For now, don't analyze code that deals with Truffle ASTs.
+    unannotatedSubPackages.addAll("org.pkl.core.ast", "org.pkl.core.stdlib")
+  }
+}
+
 tasks.compileKotlin { enabled = false }

 tasks.test {
@@ -39,6 +39,7 @@ import javax.lang.model.element.Modifier;
 import javax.lang.model.element.PackageElement;
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.type.TypeMirror;
+import org.jspecify.annotations.Nullable;

 /**
 * Generates a subclass of {@code org.pkl.core.stdlib.registry.ExternalMemberRegistry} for each
@@ -114,6 +115,7 @@ public final class MemberRegistryGenerator extends AbstractProcessor {
        Comparator.comparing(
                (TypeElement element) -> {
                  var enclosingElement = element.getEnclosingElement();
+                  assert enclosingElement != null;
                  return enclosingElement.getKind() == ElementKind.PACKAGE
                      ? ""
                      : enclosingElement.getSimpleName().toString();
@@ -155,6 +157,7 @@ public final class MemberRegistryGenerator extends AbstractProcessor {

    for (var nodeClass : nodeClasses) {
      var enclosingClass = nodeClass.getEnclosingElement();
+      assert enclosingClass != null;

      var pklClassName = getAnnotatedPklName(enclosingClass);
      if (pklClassName == null) {
@@ -226,7 +229,7 @@ public final class MemberRegistryGenerator extends AbstractProcessor {
    writeJavaFile(REGISTRY_PACKAGE_NAME, registryFactoryClass.build());
  }

-  private String getAnnotatedPklName(Element element) {
+  private @Nullable String getAnnotatedPklName(Element element) {
    for (var annotation : element.getAnnotationMirrors()) {
      var annotationName = annotation.getAnnotationType().asElement().getSimpleName().toString();

@@ -0,0 +1,4 @@
+@NullMarked
+package org.pkl.core.generator;
+
+import org.jspecify.annotations.NullMarked;
@@ -22,6 +22,7 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import org.graalvm.polyglot.Context;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.evaluatorSettings.TraceMode;
 import org.pkl.core.http.HttpClient;
 import org.pkl.core.http.HttpClientInitException;
@@ -36,7 +37,6 @@ import org.pkl.core.runtime.VmContext;
 import org.pkl.core.runtime.VmException;
 import org.pkl.core.runtime.VmImportAnalyzer;
 import org.pkl.core.runtime.VmUtils;
-import org.pkl.core.util.Nullable;

 /** Utility library for static analysis of Pkl programs. */
 public class Analyzer {
@@ -21,7 +21,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.function.BiFunction;
 import java.util.function.Function;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /**
 * A specification parsed from a valid {@code pkl:Command} submodule.
@@ -144,7 +144,7 @@ public record CommandSpec(
      @Nullable String helpText,
      boolean showAsRequired,
      BiFunction<String, URI, Object> transformEach,
-      BiFunction<List<Object>, URI, Object> transformAll,
+      BiFunction<List<Object>, URI, @Nullable Object> transformAll,
      @Nullable CompletionCandidates completionCandidates,
      @Nullable String shortName,
      String metavar,
@@ -227,7 +227,7 @@ public record CommandSpec(
      String name,
      @Nullable String helpText,
      BiFunction<String, URI, Object> transformEach,
-      BiFunction<List<Object>, URI, Object> transformAll,
+      BiFunction<List<Object>, URI, @Nullable Object> transformAll,
      @Nullable CompletionCandidates completionCandidates,
      boolean repeated)
      implements Option {
@@ -239,7 +239,7 @@ public record CommandSpec(

  /** A function used to transform command {@link State} as arguments are parsed. */
  public interface ApplyFunction {
-    State apply(Map<String, Object> options, @Nullable State parent);
+    State apply(Map<String, @Nullable Object> options, @Nullable State parent);
  }

  /**
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -16,7 +16,7 @@
 package org.pkl.core;

 import java.util.Map;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /** A container of properties. */
 public interface Composite extends Value {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -19,8 +19,8 @@ import static org.pkl.core.DataSizeUnit.*;

 import java.io.Serial;
 import java.util.Objects;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.util.MathUtils;
-import org.pkl.core.util.Nullable;

 /** Java representation of a {@code pkl.base#DataSize} value. */
 public final class DataSize implements Value {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -15,7 +15,7 @@
 */
 package org.pkl.core;

-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /**
 * The unit of a {@link DataSize}. In Pkl, data size units are represented as String {@link
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -19,8 +19,8 @@ import static org.pkl.core.DurationUnit.*;

 import java.io.Serial;
 import java.util.Objects;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.util.DurationUtils;
-import org.pkl.core.util.Nullable;

 /** Java representation of a {@code pkl.base#Duration} value. */
 public final class Duration implements Value {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -17,7 +17,7 @@ package org.pkl.core;

 import java.time.temporal.ChronoUnit;
 import java.util.concurrent.TimeUnit;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /**
 * The unit of a {@link Duration}. In Pkl, duration units are represented as String {@link
@@ -19,6 +19,7 @@ import com.oracle.truffle.api.TruffleOptions;
 import java.nio.file.Path;
 import java.util.*;
 import java.util.regex.Pattern;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.SecurityManagers.StandardBuilder;
 import org.pkl.core.evaluatorSettings.PklEvaluatorSettings.ExternalReader;
 import org.pkl.core.evaluatorSettings.TraceMode;
@@ -33,7 +34,6 @@ import org.pkl.core.resource.ResourceReader;
 import org.pkl.core.resource.ResourceReaders;
 import org.pkl.core.runtime.LoggerImpl;
 import org.pkl.core.util.IoUtils;
-import org.pkl.core.util.Nullable;

 /** A builder for an {@link Evaluator}. Can be reused to build multiple evaluators. */
@SuppressWarnings({"UnusedReturnValue", "unused"})
@@ -56,7 +56,7 @@ public final class EvaluatorBuilder {

  private final Map<String, String> externalProperties = new HashMap<>();

-  private @Nullable java.time.Duration timeout;
+  private java.time.@Nullable Duration timeout;

  private @Nullable Path moduleCacheDir = IoUtils.getDefaultModuleCacheDir();

@@ -386,7 +386,7 @@ public final class EvaluatorBuilder {
  /**
   * Sets an evaluation timeout to be enforced by the {@link Evaluator}'s {@code evaluate} methods.
   */
-  public EvaluatorBuilder setTimeout(@Nullable java.time.Duration timeout) {
+  public EvaluatorBuilder setTimeout(java.time.@Nullable Duration timeout) {
    this.timeout = timeout;
    return this;
  }
@@ -30,6 +30,7 @@ import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Supplier;
 import org.graalvm.polyglot.Context;
+import org.jspecify.annotations.Nullable;
 import org.msgpack.core.MessageBufferPacker;
 import org.msgpack.core.MessagePack;
 import org.pkl.core.ast.ConstantValueNode;
@@ -61,7 +62,6 @@ import org.pkl.core.runtime.VmValue;
 import org.pkl.core.runtime.VmValueRenderer;
 import org.pkl.core.util.ErrorMessages;
 import org.pkl.core.util.IoUtils;
-import org.pkl.core.util.Nullable;

 public final class EvaluatorImpl implements Evaluator {
  private final StackFrameTransformer frameTransformer;
@@ -307,7 +307,7 @@ public final class EvaluatorImpl implements Evaluator {
                  reservedFlagShortNames,
                  (fileOutput) -> new FileOutputImpl(this, fileOutput));
          run.accept(commandRunner.parse(module));
-          return null;
+          return true; // return value is not used; returning null would violate nullness
        });
  }

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -20,7 +20,7 @@ import java.io.Serializable;
 import java.util.List;
 import java.util.Objects;
 import java.util.Set;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /** Common base class for TypeAlias, PClass, PClass.Property, and PClass.Method. */
 public abstract class Member implements Serializable {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -17,8 +17,8 @@ package org.pkl.core;

 import java.net.URI;
 import java.util.*;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.util.LateInit;
-import org.pkl.core.util.Nullable;

 /** Describes the property, method and class members of a module. */
 public final class ModuleSchema {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -18,8 +18,8 @@ package org.pkl.core;
 import java.io.File;
 import java.net.URI;
 import java.nio.file.Path;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.runtime.VmUtils;
-import org.pkl.core.util.Nullable;

 /**
 * A representation for a Pkl module's source URI, and optionally its source text.
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -17,7 +17,7 @@ package org.pkl.core;

 import java.io.Serial;
 import java.util.*;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /** Java representation of a {@code pkl.base#Class} value. */
 public final class PClass extends Member implements Value {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -22,7 +22,7 @@ import java.io.Serializable;
 import java.net.URI;
 import java.util.*;
 import java.util.regex.Pattern;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /** Information about a Pkl class and its Java representation. */
@SuppressWarnings("rawtypes")
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ import java.io.Serial;
 import java.net.URI;
 import java.util.Map;
 import java.util.Objects;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /** Java representation of a Pkl module. */
 public final class PModule extends PObject {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -18,7 +18,7 @@ package org.pkl.core;
 import java.io.Serial;
 import java.util.Map;
 import java.util.Objects;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /** Java representation of a Pkl object. */
 public class PObject implements Composite {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -18,10 +18,12 @@ package org.pkl.core;
 import java.io.Serial;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
-import org.pkl.core.util.Nullable;
+import java.util.Objects;
+import org.jspecify.annotations.Nullable;

 /** Java representation of a {@code pkl.base#Pair} value. */
-public final class Pair<F, S> implements Value, Iterable<Object> {
+public final class Pair<F extends @Nullable Object, S extends @Nullable Object>
+    implements Value, Iterable<@Nullable Object> {
  @Serial private static final long serialVersionUID = 0L;

  private final F first;
@@ -44,7 +46,7 @@ public final class Pair<F, S> implements Value, Iterable<Object> {
  }

  @Override
-  public Iterator<Object> iterator() {
+  public Iterator<@Nullable Object> iterator() {
    return new Iterator<>() {
      int pos = 0;

@@ -54,7 +56,7 @@ public final class Pair<F, S> implements Value, Iterable<Object> {
      }

      @Override
-      public Object next() {
+      public @Nullable Object next() {
        return switch (pos++) {
          case 0 -> first;
          case 1 -> second;
@@ -83,12 +85,12 @@ public final class Pair<F, S> implements Value, Iterable<Object> {
  public boolean equals(@Nullable Object obj) {
    if (this == obj) return true;
    if (!(obj instanceof Pair<?, ?> other)) return false;
-    return first.equals(other.first) && second.equals(other.second);
+    return Objects.equals(first, other.first) && Objects.equals(second, other.second);
  }

  @Override
  public int hashCode() {
-    return first.hashCode() * 31 + second.hashCode();
+    return Objects.hashCode(first) * 31 + Objects.hashCode(second);
  }

  @Override
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -15,16 +15,18 @@
 */
 package org.pkl.core;

+import org.jspecify.annotations.Nullable;
+
 public class PklException extends RuntimeException {
-  public PklException(String message, Throwable cause) {
+  public PklException(@Nullable String message, @Nullable Throwable cause) {
    super(message, cause);
  }

-  public PklException(String message) {
+  public PklException(@Nullable String message) {
    super(message);
  }

-  public PklException(Throwable cause) {
+  public PklException(@Nullable Throwable cause) {
    super(cause);
  }
 }
@@ -21,7 +21,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.regex.Pattern;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.util.properties.PropertiesUtils;

 // To instantiate this class, use ValueRenderers.properties().
@@ -18,7 +18,7 @@ package org.pkl.core;
 import java.io.IOException;
 import java.net.URI;
 import java.nio.file.Path;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /**
 * Enforces a security model during {@link Evaluator evaluation}.
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ import java.nio.file.Path;
 import java.util.Collection;
 import java.util.List;
 import java.util.regex.Pattern;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /**
 * Parent interface to builder classes for configuring a {@link SecurityManager}.
@@ -45,8 +45,7 @@ public interface SecurityManagerBuilder<B extends SecurityManagerBuilder<B>> {

  B setRootDir(@Nullable Path rootDir);

-  @Nullable
-  Path getRootDir();
+  @Nullable Path getRootDir();

  SecurityManager build();
 }
@@ -23,9 +23,9 @@ import java.nio.file.Path;
 import java.util.*;
 import java.util.function.Function;
 import java.util.regex.Pattern;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.util.ErrorMessages;
 import org.pkl.core.util.IoUtils;
-import org.pkl.core.util.Nullable;

 /** A provider for {@link SecurityManager}s. */
 public final class SecurityManagers {
@@ -273,7 +273,7 @@ public final class SecurityManagers {

    private final List<Pattern> allowedResources = new ArrayList<>();

-    private Path rootDir;
+    private @Nullable Path rootDir;

    private StandardBuilder() {}

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -17,7 +17,7 @@ package org.pkl.core;

 import java.util.List;
 import java.util.Objects;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /** An element of a Pkl stack trace. */
 // better name would be `StackTraceElement`
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -17,7 +17,7 @@ package org.pkl.core;

 import java.util.ArrayList;
 import java.util.List;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /**
 * The results of testing a Pkl test module.
@@ -301,7 +301,7 @@ public record TestResults(
   * @param message The message of the underlying exception.
   * @param exception The exception thrown by Pkl
   */
-  public record Error(String message, PklException exception) {}
+  public record Error(@Nullable String message, PklException exception) {}

  /**
   * Indicates that an assertion failed.
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -18,8 +18,8 @@ package org.pkl.core;
 import java.io.Serial;
 import java.util.List;
 import java.util.Set;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.util.LateInit;
-import org.pkl.core.util.Nullable;

 /** Java representation of a {@code pkl.base#TypeAlias} value. */
 public final class TypeAlias extends Member implements Value {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.regex.Pattern;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;

 /** Visitor for data models generated by [Evaluator]. */
 public interface ValueVisitor {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -17,8 +17,8 @@ package org.pkl.core;

 import java.util.*;
 import java.util.regex.*;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.util.LateInit;
-import org.pkl.core.util.Nullable;

 /**
 * A <a href="https://semver.org/spec/v2.0.0.html">semantic version</a>.
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -20,7 +20,7 @@ import java.io.UncheckedIOException;
 import java.io.Writer;
 import java.util.*;
 import java.util.regex.Pattern;
-import org.pkl.core.util.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.util.yaml.snake.YamlUtils;
 import org.snakeyaml.engine.v2.api.ConstructNode;
 import org.snakeyaml.engine.v2.api.DumpSettings;
@@ -18,10 +18,10 @@ package org.pkl.core.ast;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.member.DefaultPropertyBodyNode;
 import org.pkl.core.runtime.VmExceptionBuilder;
 import org.pkl.core.runtime.VmLanguage;
-import org.pkl.core.util.Nullable;

 public abstract class MemberNode extends PklRootNode {
  @Child protected ExpressionNode bodyNode;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -22,9 +22,9 @@ import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.NodeInfo;
 import com.oracle.truffle.api.nodes.RootNode;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.type.VmTypeMismatchException;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

@NodeInfo(language = "Pkl")
@TypeSystemReference(VmTypes.class)
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -18,8 +18,8 @@ package org.pkl.core.ast.builder;
 import com.oracle.truffle.api.source.Source;
 import com.oracle.truffle.api.source.SourceSection;
 import java.util.List;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.runtime.VmExceptionBuilder;
-import org.pkl.core.util.Nullable;
 import org.pkl.parser.BaseParserVisitor;
 import org.pkl.parser.Span;
 import org.pkl.parser.syntax.DocComment;
@@ -33,6 +33,7 @@ import java.util.function.BiFunction;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
 import org.graalvm.collections.EconomicMap;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.PClassInfo;
 import org.pkl.core.PklBugException;
 import org.pkl.core.SecurityManagerException;
@@ -183,7 +184,6 @@ import org.pkl.core.stdlib.registry.MemberRegistryFactory;
 import org.pkl.core.util.CollectionUtils;
 import org.pkl.core.util.EconomicMaps;
 import org.pkl.core.util.IoUtils;
-import org.pkl.core.util.Nullable;
 import org.pkl.core.util.Pair;
 import org.pkl.parser.Span;
 import org.pkl.parser.syntax.Annotation;
@@ -2694,7 +2694,7 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
    return builder;
  }

-  private @Nullable FrameDescriptor.Builder createFrameDescriptorBuilder(ObjectBody body) {
+  private FrameDescriptor.@Nullable Builder createFrameDescriptorBuilder(ObjectBody body) {
    if (body.getParameters().isEmpty()) return null;

    var builder = FrameDescriptor.newBuilder(body.getParameters().size());
@@ -2746,7 +2746,7 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
        .withMemberName(symbolTable.getCurrentScope().getQualifiedName());
  }

-  private @Nullable SymbolTable.Scope getParentLexicalScope() {
+  private SymbolTable.@Nullable Scope getParentLexicalScope() {
    var parent = symbolTable.getCurrentScope().getLexicalScope().getParent();
    if (parent != null) return parent.getLexicalScope();
    return null;
@@ -21,13 +21,13 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.builder.ImportsAndReadsParser.Entry;
 import org.pkl.core.module.ModuleKey;
 import org.pkl.core.module.ResolvedModuleKey;
 import org.pkl.core.runtime.VmExceptionBuilder;
 import org.pkl.core.runtime.VmUtils;
 import org.pkl.core.util.IoUtils;
-import org.pkl.core.util.Nullable;
 import org.pkl.parser.Parser;
 import org.pkl.parser.ParserError;
 import org.pkl.parser.syntax.Expr;
@@ -19,6 +19,7 @@ import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.FrameDescriptor.Builder;
 import java.util.*;
 import java.util.function.Function;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.TypeParameter;
 import org.pkl.core.ast.ConstantNode;
 import org.pkl.core.ast.ExpressionNode;
@@ -28,7 +29,6 @@ import org.pkl.core.runtime.Identifier;
 import org.pkl.core.runtime.ModuleInfo;
 import org.pkl.core.runtime.VmDataSize;
 import org.pkl.core.runtime.VmDuration;
-import org.pkl.core.util.Nullable;
 import org.pkl.parser.Lexer;

 public final class SymbolTable {
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.builder;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -21,9 +21,9 @@ import com.oracle.truffle.api.dsl.NodeChild;
 import com.oracle.truffle.api.dsl.Specialization;
 import com.oracle.truffle.api.nodes.NodeInfo;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

@NodeInfo(shortName = "==")
@NodeChild(value = "leftNode", type = ExpressionNode.class)
@@ -21,9 +21,9 @@ import com.oracle.truffle.api.dsl.NodeChild;
 import com.oracle.truffle.api.dsl.Specialization;
 import com.oracle.truffle.api.nodes.NodeInfo;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.runtime.VmValue;
-import org.pkl.core.util.Nullable;

@NodeInfo(shortName = "!=")
@NodeChild(value = "leftNode", type = ExpressionNode.class)
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.expression.binary;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -23,11 +23,11 @@ import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.ExplodeLoop;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 public abstract class GeneratorForNode extends GeneratorMemberNode {
  private final FrameDescriptor generatorDescriptor;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -26,12 +26,12 @@ import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.ExplodeLoop;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.expression.literal.AmendFunctionNode;
 import org.pkl.core.ast.expression.literal.ObjectLiteralNode;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 /** An object literal node that contains at least one for- or when-expression. */
@ImportStatic(BaseModule.class)
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.expression.generator;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -22,6 +22,7 @@ import com.oracle.truffle.api.frame.*;
 import com.oracle.truffle.api.nodes.ExplodeLoop;
 import com.oracle.truffle.api.nodes.IndirectCallNode;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.PklNode;
 import org.pkl.core.ast.PklRootNode;
@@ -31,7 +32,6 @@ import org.pkl.core.ast.member.FunctionNode;
 import org.pkl.core.ast.member.Lambda;
 import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 public final class AmendFunctionNode extends PklNode {
  private final boolean isCustomThisScope;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -17,11 +17,11 @@ package org.pkl.core.ast.expression.literal;

 import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.frame.VirtualFrame;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 public final class CheckIsAnnotationClassNode extends ExpressionNode {
  @Child private UnresolvedTypeNode unresolvedTypeNode;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -22,11 +22,11 @@ import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
 import org.graalvm.collections.UnmodifiableEconomicMap;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.member.ObjectMember;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 /**
 * Object literal that contains entries (and possibly properties) but not elements. Additionally,
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -25,12 +25,12 @@ import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.ExplodeLoop;
 import com.oracle.truffle.api.source.SourceSection;
 import org.graalvm.collections.UnmodifiableEconomicMap;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.member.ObjectMember;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
 import org.pkl.core.util.EconomicMaps;
-import org.pkl.core.util.Nullable;

 /**
 * Object literal that contains both elements and entries (and possibly properties). Example: `new
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -21,12 +21,12 @@ import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
 import org.graalvm.collections.UnmodifiableEconomicMap;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.member.ObjectMember;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
 import org.pkl.core.util.EconomicMaps;
-import org.pkl.core.util.Nullable;

 /**
 * Object literal that contains elements (and possibly properties) but not entries. Example: `new
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -24,13 +24,13 @@ import com.oracle.truffle.api.nodes.ExplodeLoop;
 import com.oracle.truffle.api.source.SourceSection;
 import org.graalvm.collections.EconomicMap;
 import org.graalvm.collections.UnmodifiableEconomicMap;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.member.ObjectMember;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
 import org.pkl.core.runtime.VmException.ProgramValue;
 import org.pkl.core.util.EconomicMaps;
-import org.pkl.core.util.Nullable;

 /**
 * Object literal that contains entries (and possibly properties) but not elements. Additionally, at
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -19,12 +19,12 @@ import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.member.FunctionNode;
 import org.pkl.core.ast.member.UnresolvedFunctionNode;
 import org.pkl.core.runtime.VmFunction;
 import org.pkl.core.runtime.VmUtils;
-import org.pkl.core.util.Nullable;

 public final class FunctionLiteralNode extends ExpressionNode {
  private @Child UnresolvedFunctionNode unresolvedFunctionNode;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import com.oracle.truffle.api.dsl.NodeChild;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
@@ -28,7 +29,6 @@ import org.pkl.core.runtime.VmClass;
 import org.pkl.core.runtime.VmFunction;
 import org.pkl.core.runtime.VmLanguage;
 import org.pkl.core.runtime.VmUtils;
-import org.pkl.core.util.Nullable;

 // IDEA: don't materialize frames when all members are constants
@NodeChild(value = "parentNode", type = ExpressionNode.class)
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -23,11 +23,11 @@ import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.ExplodeLoop;
 import com.oracle.truffle.api.source.SourceSection;
 import org.graalvm.collections.UnmodifiableEconomicMap;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.member.ObjectMember;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 /** Object literal that contains properties but not elements or entries. */
 // IDEA: don't materialize frame when all members are constants
@@ -26,13 +26,13 @@ import com.oracle.truffle.api.nodes.UnexpectedResultException;
 import com.oracle.truffle.api.source.SourceSection;
 import org.graalvm.collections.EconomicMap;
 import org.graalvm.collections.UnmodifiableEconomicMap;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.member.ObjectMember;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
 import org.pkl.core.runtime.VmException.ProgramValue;
 import org.pkl.core.util.EconomicMaps;
-import org.pkl.core.util.Nullable;

 /**
 * Base class for object literal nodes specialized for a certain mix of property/entry/element
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.expression.literal;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -23,11 +23,11 @@ import com.oracle.truffle.api.nodes.DirectCallNode;
 import com.oracle.truffle.api.nodes.IndirectCallNode;
 import com.oracle.truffle.api.nodes.NodeInfo;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.MemberLookupMode;
 import org.pkl.core.ast.member.ClassProperty;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

@NodeInfo(shortName = ".")
@ImportStatic(BaseModule.class)
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.expression.member;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.expression;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.expression.primary;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.expression.ternary;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -22,13 +22,13 @@ import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.net.URI;
 import java.net.URISyntaxException;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.SecurityManagerException;
 import org.pkl.core.externalreader.ExternalReaderProcessException;
 import org.pkl.core.module.ModuleKey;
 import org.pkl.core.packages.PackageLoadError;
 import org.pkl.core.runtime.VmContext;
 import org.pkl.core.util.IoUtils;
-import org.pkl.core.util.Nullable;

 public abstract class AbstractReadNode extends UnaryExpressionNode {
  protected final ModuleKey currentModule;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -41,7 +41,9 @@ public class ReadGlobMemberBodyNode extends ExpressionNode {
  private Object readResource(VmObjectLike mapping, String path) {
    @SuppressWarnings("unchecked")
    var globElements = (Map<String, ResolvedGlobElement>) mapping.getExtraStorage();
-    var resourceUri = VmUtils.getMapValue(globElements, path).uri();
+    var globElement = VmUtils.getMapValue(globElements, path);
+    assert globElement != null;
+    var resourceUri = globElement.uri();
    var resource = VmContext.get(this).getResourceManager().read(resourceUri, this).orElse(null);
    if (resource == null) {
      CompilerDirectives.transferToInterpreter();
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.expression.unary;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.frame;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -18,8 +18,8 @@ package org.pkl.core.ast.internal;
 import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.dsl.NodeChild;
 import com.oracle.truffle.api.dsl.Specialization;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
-import org.pkl.core.util.Nullable;

 /** Ensures that `childNode` isn't optimized away. */
@NodeChild(value = "childNode", type = ExpressionNode.class)
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.internal;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.lambda;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -18,10 +18,10 @@ package org.pkl.core.ast.member;
 import com.oracle.truffle.api.source.SourceSection;
 import java.util.ArrayList;
 import java.util.List;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.runtime.Identifier;
 import org.pkl.core.runtime.VmClass;
 import org.pkl.core.runtime.VmTyped;
-import org.pkl.core.util.Nullable;

 public abstract class ClassMember extends Member {
  protected final SourceSection @Nullable [] docComment;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -20,12 +20,12 @@ import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.source.SourceSection;
 import java.util.List;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.PClass;
 import org.pkl.core.TypeParameter;
 import org.pkl.core.ast.VmModifier;
 import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 public final class ClassMethod extends ClassMember {
  private final List<TypeParameter> typeParameters;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -23,6 +23,7 @@ import com.oracle.truffle.api.source.SourceSection;
 import java.util.ArrayList;
 import java.util.List;
 import org.graalvm.collections.EconomicMap;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.PClassInfo;
 import org.pkl.core.TypeParameter;
 import org.pkl.core.ast.ExpressionNode;
@@ -30,7 +31,6 @@ import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
 import org.pkl.core.util.LateInit;
-import org.pkl.core.util.Nullable;

@NodeInfo(shortName = "class")
 public final class ClassNode extends ExpressionNode {
@@ -102,12 +102,8 @@ public final class ClassNode extends ExpressionNode {
      prototype.setExtraStorage(moduleInfo);
      prototype.addProperties(prototypeMembers);
    } else {
-      prototype =
-          new VmTyped(
-              frame.materialize(),
-              null, // initialized later by VmClass
-              null, // initialized later by VmClass
-              prototypeMembers);
+      // parent and clazz will be initialized later by VmClass
+      prototype = new VmTyped(frame.materialize(), null, prototypeMembers);
    }

    var annotations = new ArrayList<VmTyped>(annotationNodes.length);
@@ -17,11 +17,11 @@ package org.pkl.core.ast.member;

 import com.oracle.truffle.api.source.SourceSection;
 import java.util.List;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.Member.SourceLocation;
 import org.pkl.core.PClass;
 import org.pkl.core.ast.VmModifier;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 public final class ClassProperty extends ClassMember {
  private final @Nullable PropertyTypeNode typeNode;
@@ -18,10 +18,10 @@ package org.pkl.core.ast.member;
 import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.runtime.Identifier;
 import org.pkl.core.runtime.VmUtils;
-import org.pkl.core.util.Nullable;

 /**
 * Property body for properties that don't have an explicit body. Returns the default value for the
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -22,6 +22,7 @@ import com.oracle.truffle.api.dsl.Specialization;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.IndirectCallNode;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.expression.primary.GetReceiverNode;
 import org.pkl.core.runtime.VmDynamic;
@@ -29,7 +30,6 @@ import org.pkl.core.runtime.VmLanguage;
 import org.pkl.core.runtime.VmListing;
 import org.pkl.core.runtime.VmMapping;
 import org.pkl.core.runtime.VmUtils;
-import org.pkl.core.util.Nullable;

 /** Equivalent of {@link TypedPropertyNode} for elements/entries. */
 public abstract class ElementOrEntryNode extends RegularMemberNode {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -22,6 +22,7 @@ import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.ExplodeLoop;
 import com.oracle.truffle.api.source.SourceSection;
 import java.util.List;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.Member.SourceLocation;
 import org.pkl.core.PClass;
 import org.pkl.core.PType;
@@ -31,7 +32,6 @@ import org.pkl.core.ast.VmModifier;
 import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.runtime.*;
 import org.pkl.core.util.CollectionUtils;
-import org.pkl.core.util.Nullable;
 import org.pkl.core.util.Pair;

 public final class FunctionNode extends RegularMemberNode {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -16,8 +16,8 @@
 package org.pkl.core.ast.member;

 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.VmModifier;
-import org.pkl.core.util.Nullable;

 public class Lambda extends Member {
  public Lambda(SourceSection sourceSection, String qualifiedName) {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -18,10 +18,10 @@ package org.pkl.core.ast.member;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.PklRootNode;
 import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.runtime.VmLanguage;
-import org.pkl.core.util.Nullable;

 /** Performs a typecast on a Mapping entry value, or a Listing element. */
 public final class ListingOrMappingTypeCastNode extends PklRootNode {
@@ -18,12 +18,12 @@ package org.pkl.core.ast.member;
 import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.VmLanguage;
 import org.pkl.core.util.LateInit;
-import org.pkl.core.util.Nullable;

 public final class LocalTypedPropertyNode extends RegularMemberNode {
  private final VmLanguage language;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -16,9 +16,9 @@
 package org.pkl.core.ast.member;

 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.VmModifier;
 import org.pkl.core.runtime.Identifier;
-import org.pkl.core.util.Nullable;

 public abstract class Member {
  protected final SourceSection sourceSection;
@@ -19,13 +19,13 @@ import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
 import com.oracle.truffle.api.RootCallTarget;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ConstantNode;
 import org.pkl.core.ast.MemberNode;
 import org.pkl.core.ast.VmModifier;
 import org.pkl.core.runtime.Identifier;
 import org.pkl.core.runtime.VmDynamic;
 import org.pkl.core.runtime.VmUtils;
-import org.pkl.core.util.Nullable;

 public final class ObjectMember extends Member {

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -20,12 +20,12 @@ import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
 import org.pkl.core.util.LateInit;
-import org.pkl.core.util.Nullable;

 public final class ObjectMethodNode extends RegularMemberNode {
  private final VmLanguage language;
@@ -19,12 +19,12 @@ import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.PType;
 import org.pkl.core.ast.PklRootNode;
 import org.pkl.core.ast.type.TypeNode;
 import org.pkl.core.ast.type.TypeNode.UnknownTypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 public final class PropertyTypeNode extends PklRootNode {
  private final String qualifiedPropertyName;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -17,10 +17,10 @@ package org.pkl.core.ast.member;

 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.MemberNode;
 import org.pkl.core.runtime.VmLanguage;
-import org.pkl.core.util.Nullable;

 /** A {@code MemberNode} that belongs to a single {@link Member}. */
 public abstract class RegularMemberNode extends MemberNode {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -18,10 +18,10 @@ package org.pkl.core.ast.member;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.MemberNode;
 import org.pkl.core.runtime.VmLanguage;
-import org.pkl.core.util.Nullable;

 /** A {@code MemberNode} that is shared between multiple {@linkplain Member members}. */
 public class SharedMemberNode extends MemberNode {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -21,13 +21,13 @@ import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
 import java.util.ArrayList;
 import java.util.List;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.TypeParameter;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.VmTypeAlias;
 import org.pkl.core.runtime.VmTyped;
 import org.pkl.core.runtime.VmUtils;
-import org.pkl.core.util.Nullable;

 public final class TypeAliasNode extends ExpressionNode {
  private final SourceSection headerSection;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -22,10 +22,10 @@ import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.DirectCallNode;
 import com.oracle.truffle.api.nodes.IndirectCallNode;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.expression.primary.GetOwnerNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 /** A property definition that does not have a type annotation but should be type-checked. */
 public abstract class TypeCheckedPropertyNode extends RegularMemberNode {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -18,12 +18,12 @@ package org.pkl.core.ast.member;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.PklNode;
 import org.pkl.core.runtime.Identifier;
 import org.pkl.core.runtime.VmClass;
 import org.pkl.core.runtime.VmLanguage;
-import org.pkl.core.util.Nullable;

 public abstract class UnresolvedClassMemberNode extends PklNode {
  protected final SourceSection headerSection;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -18,11 +18,11 @@ package org.pkl.core.ast.member;
 import com.oracle.truffle.api.CompilerAsserts;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.PklNode;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 public final class UnresolvedFunctionNode extends PklNode {
  private final VmLanguage language;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -20,12 +20,12 @@ import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
 import java.util.List;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.TypeParameter;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.VmModifier;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 public final class UnresolvedMethodNode extends UnresolvedClassMemberNode {
  private final int parameterCount;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -19,11 +19,11 @@ import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.ast.VmModifier;
 import org.pkl.core.ast.type.UnresolvedTypeNode;
 import org.pkl.core.runtime.*;
-import org.pkl.core.util.Nullable;

 public final class UnresolvedPropertyNode extends UnresolvedClassMemberNode {
  private final SourceSection propertyNameSection;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -17,9 +17,9 @@ package org.pkl.core.ast.member;

 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.runtime.VmLanguage;
-import org.pkl.core.util.Nullable;

 public final class UntypedObjectMemberNode extends RegularMemberNode {
  public UntypedObjectMemberNode(
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.member;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.repl;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -19,9 +19,9 @@ import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.PklRootNode;
 import org.pkl.core.runtime.VmLanguage;
-import org.pkl.core.util.Nullable;

 /** Root node for a mixin used as default value for type `Mixin<Foo>`. */
 public final class IdentityMixinNode extends PklRootNode {
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2026 Apple Inc. and the Pkl project authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -17,11 +17,11 @@ package org.pkl.core.ast.type;

 import com.oracle.truffle.api.nodes.IndirectCallNode;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.runtime.Identifier;
 import org.pkl.core.runtime.VmObjectLike;
 import org.pkl.core.runtime.VmTyped;
-import org.pkl.core.util.Nullable;

 public abstract class ResolveDeclaredTypeNode extends ExpressionNode {
  @Child private IndirectCallNode callNode = IndirectCallNode.create();
@@ -33,6 +33,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.PType;
 import org.pkl.core.PType.StringLiteral;
 import org.pkl.core.PklBugException;
@@ -52,8 +54,6 @@ import org.pkl.core.util.EconomicMaps;
 import org.pkl.core.util.EconomicSets;
 import org.pkl.core.util.LateInit;
 import org.pkl.core.util.MutableBoolean;
-import org.pkl.core.util.Nonnull;
-import org.pkl.core.util.Nullable;

 public abstract class TypeNode extends PklNode {

@@ -2689,7 +2689,7 @@ public abstract class TypeNode extends PklNode {
    }

    @Override
-    public @Nonnull VmTypeAlias getVmTypeAlias() {
+    public @NonNull VmTypeAlias getVmTypeAlias() {
      return typeAlias;
    }

@@ -19,9 +19,9 @@ import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.NodeInfo;
 import com.oracle.truffle.api.source.SourceSection;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.ast.ExpressionNode;
 import org.pkl.core.runtime.VmLanguage;
-import org.pkl.core.util.Nullable;

@NodeInfo(shortName = "is")
 public final class TypeTestNode extends ExpressionNode {
@@ -22,6 +22,7 @@ import com.oracle.truffle.api.nodes.Node;
 import com.oracle.truffle.api.source.SourceSection;
 import java.util.*;
 import java.util.stream.Collectors;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.StackFrame;
 import org.pkl.core.ValueFormatter;
 import org.pkl.core.ast.type.TypeNode.UnionTypeNode;
@@ -29,7 +30,6 @@ import org.pkl.core.runtime.*;
 import org.pkl.core.runtime.VmException.ProgramValue;
 import org.pkl.core.util.AnsiStringBuilder;
 import org.pkl.core.util.ErrorMessages;
-import org.pkl.core.util.Nullable;

 /**
 * Indicates that a type check failed. [TypeNode]s use this exception instead of [VmException] to
@@ -1,4 +1,4 @@
-@NonnullByDefault
+@NullMarked
 package org.pkl.core.ast.type;

-import org.pkl.core.util.NonnullByDefault;
+import org.jspecify.annotations.NullMarked;
@@ -29,6 +29,7 @@ import java.util.function.BiFunction;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
+import org.jspecify.annotations.Nullable;
 import org.pkl.core.Duration;
 import org.pkl.core.PNull;
 import org.pkl.core.PObject;
@@ -39,7 +40,6 @@ import org.pkl.core.Value;
 import org.pkl.core.util.ErrorMessages;
 import org.pkl.core.util.GlobResolver;
 import org.pkl.core.util.GlobResolver.InvalidGlobPatternException;
-import org.pkl.core.util.Nullable;

 /** Java version of {@code pkl.EvaluatorSettings}. */
 public record PklEvaluatorSettings(
--- a/Show More
+++ b/Show More