Address warning diagnostics (#1395)

This addressess various warning diagnostics throughout the codebase.

pkl-core/src/main/java/org/pkl/core/JsonRenderer.java

@@ -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.
@@ -105,7 +105,8 @@ final class JsonRenderer implements ValueRenderer {
     @Override
     public void visitBytes(byte[] value) {
       throw new RendererException(
-          String.format("Values of type `Bytes` cannot be rendered as JSON. Value: %s", value));
+          String.format(
+              "Values of type `Bytes` cannot be rendered as JSON. Value: %s", (Object) value));
     }
 
     @Override

pkl-core/src/main/java/org/pkl/core/PropertiesRenderer.java

@@ -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.
@@ -110,7 +110,8 @@ final class PropertiesRenderer implements ValueRenderer {
     public String convertBytes(byte[] value) {
       throw new RendererException(
           String.format(
-              "Values of type `Bytes` cannot be rendered as Properties. Value: %s", value));
+              "Values of type `Bytes` cannot be rendered as Properties. Value: %s",
+              (Object) value));
     }
 
     @Override

pkl-core/src/main/java/org/pkl/core/ast/builder/AstBuilder.java

@@ -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.
@@ -2449,8 +2449,7 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
       if (dataSizeUnit != null) {
         //noinspection ConstantConditions
         return new ConstantValueNode(
-            sourceSection,
-            new VmDataSize(((IntLiteralNode) receiver).executeInt(null), dataSizeUnit));
+            sourceSection, new VmDataSize(intLiteralNode.executeInt(null), dataSizeUnit));
       }
     }
 
@@ -2465,8 +2464,7 @@ public class AstBuilder extends AbstractAstBuilder<Object> {
       if (dataSizeUnit != null) {
         //noinspection ConstantConditions
         return new ConstantValueNode(
-            sourceSection,
-            new VmDataSize(((FloatLiteralNode) receiver).executeFloat(null), dataSizeUnit));
+            sourceSection, new VmDataSize(floatLiteralNode.executeFloat(null), dataSizeUnit));
       }
     }
 

pkl-core/src/main/java/org/pkl/core/ast/expression/binary/NotEqualNode.java

@@ -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.
@@ -100,6 +100,7 @@ public abstract class NotEqualNode extends ExpressionNode {
     return true;
   }
 
+  @SuppressWarnings("JavaExistingMethodCanBeUsed")
   protected static boolean isIncompatibleTypes(Object left, Object right) {
     var leftClass = left.getClass();
     var rightClass = right.getClass();

pkl-core/src/main/java/org/pkl/core/ast/expression/literal/SpecializedObjectLiteralNode.java

@@ -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.
@@ -67,7 +67,6 @@ public abstract class SpecializedObjectLiteralNode extends ObjectLiteralNode {
 
   // only runs once per VmClass (which often means once per PropertiesLiteralNode)
   // unless an XYZUncached specialization is active
-  @SuppressWarnings("ExtractMethodRecommender")
   @TruffleBoundary
   @Idempotent
   protected boolean checkIsValidTypedAmendment(Object parent) {

pkl-core/src/main/java/org/pkl/core/project/ProjectPackager.java

@@ -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.
@@ -62,7 +62,6 @@ import org.pkl.core.util.ErrorMessages;
 import org.pkl.core.util.GlobResolver;
 import org.pkl.core.util.GlobResolver.InvalidGlobPatternException;
 import org.pkl.core.util.IoUtils;
-import org.pkl.core.util.Nullable;
 
 /**
  * Given a list of project directories, prepares artifacts to be published as a package.
@@ -441,7 +440,7 @@ public final class ProjectPackager {
     }
   }
 
-  private @Nullable List<ImportsAndReadsParser.Entry> getImportsAndReads(Path pklModulePath) {
+  private List<ImportsAndReadsParser.Entry> getImportsAndReads(Path pklModulePath) {
     try {
       var moduleKey = ModuleKeys.file(pklModulePath);
       var resolvedModuleKey = ResolvedModuleKeys.file(moduleKey, moduleKey.getUri(), pklModulePath);

pkl-core/src/main/java/org/pkl/core/runtime/MinPklVersionChecker.java

@@ -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.
@@ -63,7 +63,11 @@ final class MinPklVersionChecker {
         if (!Identifier.MIN_PKL_VERSION.toString().equals(prop.getIdentifier().getValue()))
           continue;
 
-        var versionText = prop.getExpr().text(source.toCharArray());
+        var versionTextExpr = prop.getExpr();
+        if (versionTextExpr == null) {
+          return;
+        }
+        var versionText = versionTextExpr.text(source.toCharArray());
 
         Version version;
         try {

pkl-core/src/main/java/org/pkl/core/runtime/VmBytes.java

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2025-2026 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.
@@ -37,7 +37,7 @@ public final class VmBytes extends VmValue implements Iterable<Long> {
   private final byte[] bytes;
   private @Nullable VmDataSize size;
 
-  public static VmBytes EMPTY = new VmBytes(new byte[0]);
+  public static final VmBytes EMPTY = new VmBytes(new byte[0]);
 
   @TruffleBoundary
   public static VmBytes createFromConstantNodes(ExpressionNode[] elements) {

pkl-core/src/main/java/org/pkl/core/runtime/VmDynamic.java

@@ -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.
@@ -100,7 +100,8 @@ public final class VmDynamic extends VmObject {
   @Override
   @TruffleBoundary
   public boolean equals(Object obj) {
-    if (this == obj) return true;
+    if (this == obj) // noinspection Contract
+    return true;
     if (!(obj instanceof VmDynamic other)) return false;
 
     // could use shallow force, but deep force is cached

pkl-core/src/main/java/org/pkl/core/runtime/VmImportAnalyzer.java

@@ -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.
@@ -94,9 +94,6 @@ public class VmImportAnalyzer {
     } catch (IOException err) {
       throw new VmExceptionBuilder().evalError("ioErrorLoadingModule", moduleKey.getUri()).build();
     }
-    if (importsAndReads == null) {
-      return Set.of();
-    }
     var result = new HashSet<ImportEntry>();
     for (var entry : importsAndReads) {
       if (!entry.isModule()) {

pkl-core/src/main/java/org/pkl/core/runtime/VmMapping.java

@@ -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.
@@ -119,7 +119,8 @@ public final class VmMapping extends VmListingOrMapping {
   @Override
   @TruffleBoundary
   public boolean equals(Object obj) {
-    if (this == obj) return true;
+    if (this == obj) // noinspection Contract
+    return true;
     if (!(obj instanceof VmMapping other)) return false;
 
     // could use shallow force, but deep force is cached

pkl-core/src/main/java/org/pkl/core/stdlib/base/BaseNodes.java

@@ -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.
@@ -52,14 +52,14 @@ public final class BaseNodes {
 
   public abstract static class NaN extends ExternalPropertyNode {
     @Specialization
-    protected double eval(VmTyped self) {
+    protected double eval(VmTyped ignored) {
       return Double.NaN;
     }
   }
 
   public abstract static class Infinity extends ExternalPropertyNode {
     @Specialization
-    protected double eval(VmTyped self) {
+    protected double eval(VmTyped ignored) {
       return Double.POSITIVE_INFINITY;
     }
   }

pkl-core/src/main/java/org/pkl/core/stdlib/base/DataSizeNodes.java

@@ -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.
@@ -27,7 +27,8 @@ public final class DataSizeNodes {
   private DataSizeNodes() {}
 
   @ImportStatic(MathUtils.class)
-  public abstract static class value extends ExternalPropertyNode {
+  @PklName("value")
+  public abstract static class valueProperty extends ExternalPropertyNode {
     @Specialization(guards = "isMathematicalInteger(self.getValue())")
     protected long evalInt(VmDataSize self) {
       return (long) self.getValue();

pkl-core/src/main/java/org/pkl/core/stdlib/base/DurationNodes.java

@@ -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.
@@ -29,7 +29,8 @@ public final class DurationNodes {
   private DurationNodes() {}
 
   @ImportStatic(MathUtils.class)
-  public abstract static class value extends ExternalPropertyNode {
+  @PklName("value")
+  public abstract static class valueProperty extends ExternalPropertyNode {
     @Specialization(guards = "isMathematicalInteger(self.getValue())")
     protected long evalInt(VmDuration self) {
       return (long) self.getValue();

pkl-core/src/main/java/org/pkl/core/stdlib/base/PairNodes.java

@@ -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.
@@ -18,6 +18,7 @@ package org.pkl.core.stdlib.base;
 import com.oracle.truffle.api.dsl.Specialization;
 import org.pkl.core.runtime.VmPair;
 import org.pkl.core.stdlib.ExternalPropertyNode;
+import org.pkl.core.stdlib.PklName;
 
 public final class PairNodes {
   private PairNodes() {}
@@ -43,7 +44,8 @@ public final class PairNodes {
     }
   }
 
-  public abstract static class value extends ExternalPropertyNode {
+  @PklName("value")
+  public abstract static class valueProperty extends ExternalPropertyNode {
     @Specialization
     protected Object eval(VmPair self) {
       return self.getSecond();

pkl-core/src/main/java/org/pkl/core/stdlib/test/report/JUnitReport.java

@@ -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 +20,6 @@ import java.io.Writer;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Consumer;
-import java.util.stream.Collectors;
 import org.graalvm.collections.EconomicMap;
 import org.pkl.core.TestResults;
 import org.pkl.core.TestResults.Error;
@@ -57,9 +56,8 @@ public final class JUnitReport implements TestReport {
 
   @Override
   public void summarize(List<TestResults> allTestResults, Writer writer) throws IOException {
-    var totalTests = allTestResults.stream().collect(Collectors.summingLong(r -> r.totalTests()));
-    var totalFailures =
-        allTestResults.stream().collect(Collectors.summingLong(r -> r.totalFailures()));
+    var totalTests = allTestResults.stream().mapToLong(TestResults::totalTests).sum();
+    var totalFailures = allTestResults.stream().mapToLong(TestResults::totalFailures).sum();
 
     assert aggregateSuiteName != null;
 
@@ -69,12 +67,11 @@ public final class JUnitReport implements TestReport {
             "tests", totalTests,
             "failures", totalFailures);
 
-    var tests =
-        allTestResults.stream()
-            .map(r -> buildSuite(r))
-            .collect(Collectors.toCollection(ArrayList::new));
-
-    var suite = buildXmlElement("testsuites", attrs, tests.toArray(new VmDynamic[0]));
+    var suite =
+        buildXmlElement(
+            "testsuites",
+            attrs,
+            allTestResults.stream().map(this::buildSuite).toArray(VmDynamic[]::new));
 
     writer.append(renderXML("    ", "1.0", suite));
   }

pkl-core/src/main/java/org/pkl/core/util/json/Json.java

@@ -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.
@@ -362,7 +362,7 @@ public final class Json {
     }
 
     @Override
-    public Object put(String key, Object value) {
+    public @Nullable Object put(String key, Object value) {
       return delegate.put(key, value);
     }
 

pkl-core/src/test/kotlin/org/pkl/core/parser/TrailingCommasTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2025 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2025-2026 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.
@@ -17,14 +17,11 @@ package org.pkl.core.parser
 
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
-import org.pkl.core.Evaluator
 import org.pkl.parser.Parser
 
 // tests type argument and parameter parsing with trailing commas that cannot be tested with
 // snippets because these constructs are currently only allowed in the stdlib
 class TrailingCommasTest {
-  private val evaluator = Evaluator.preconfigured()
-
   @Test
   fun `class type parameter lists parse correctly`() {
     val module =