Fix invalid prefix when generating spring boot config (#1862)

Fix invalid prefix when generating spring boot config

In Spring Boot, the prefix passed to `@ConfigurationProperties` must
be in "canonical form".

The presence of this annotation allows spring boot to directly inject
properties into a class, but is not actually needed.

The correct behavior here is to omit this annotation if the property
name does not match Spring Boot's canonical form.

pkl-codegen-kotlin/src/main/kotlin/org/pkl/codegen/kotlin/KotlinCodeGenerator.kt

@@ -22,6 +22,7 @@ import com.squareup.kotlinpoet.ParameterizedTypeName.Companion.parameterizedBy
 import java.io.StringWriter
 import java.util.*
 import org.pkl.commons.NameMapper
+import org.pkl.commons.isValidConfigurationPropertiesPrefix
 import org.pkl.core.*
 import org.pkl.core.util.CodeGeneratorUtils
 import org.pkl.core.util.IoUtils
@@ -437,7 +438,10 @@ class KotlinCodeGenerator(
             }
             propertyType is PType.Class && propertyType.pClass == pClass
           }
-        if (modulePropertiesWithMatchingType.size == 1) {
+        val singleProperty = modulePropertiesWithMatchingType.singleOrNull()
+        if (
+          singleProperty != null && singleProperty.simpleName.isValidConfigurationPropertiesPrefix
+        ) {
           // exactly one module property has this type -> make it available for direct injection
           // (potential improvement: make type available for direct injection if it occurs exactly
           // once in property tree)

pkl-codegen-kotlin/src/test/kotlin/org/pkl/codegen/kotlin/KotlinCodeGeneratorTest.kt

@@ -1470,6 +1470,56 @@ class KotlinCodeGeneratorTest {
     assertThat(kotlinCodeWithoutSpringAnnotations).compilesSuccessfully()
   }
 
+  @Test
+  fun `spring boot -- single module property has type but invalid prefix`() {
+    val javaCode =
+      generateKotlinCode(
+        """
+        module my.mod
+
+        fooBar: FooBar
+
+        class FooBar
+        """
+          .trimIndent(),
+        generateSpringBootConfig = true,
+      )
+    // "fooBar" is not a valid prefix for `@ConfigurationProperties` annotations, so no
+    // annotation is added
+    assertThat(javaCode)
+      .contains(
+        """
+        |
+        |  data class FooBar
+        """
+          .trimMargin()
+      )
+  }
+
+  @Test
+  fun `spring boot -- single module property has type and valid prefix`() {
+    val javaCode =
+      generateKotlinCode(
+        """
+        module my.mod
+
+        server: Server
+
+        class Server
+        """
+          .trimIndent(),
+        generateSpringBootConfig = true,
+      )
+    assertThat(javaCode)
+      .contains(
+        """
+        |  @ConfigurationProperties("server")
+        |  data class Server
+        """
+          .trimMargin()
+      )
+  }
+
   @Test
   fun `import module`() {
     val library =