Honor options.release for target JVM attribute

docs/changes/README.md

@@ -2,6 +2,9 @@
 
 ## [Unreleased](https://github.com/GradleUp/shadow/compare/9.0.0-rc1...HEAD) - 2025-xx-xx
 
+**Fixed**
+- Honor `options.release` for target JVM attribute. ([#1502](https://github.com/GradleUp/shadow/pull/1502))
+
 ## [9.0.0-rc1](https://github.com/GradleUp/shadow/releases/tag/9.0.0-rc1) - 2025-07-02
 
 > This release is a major update from the 8.3.x series. The plugin has been fully rewritten in Kotlin, bringing

src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/PublishingTest.kt

@@ -87,6 +87,7 @@ class PublishingTest : BasePluginTest() {
     }.toTypedArray()
     val targetJvmAttr17 = TargetJvmVersion.TARGET_JVM_VERSION_ATTRIBUTE.name to "17"
     val targetJvmAttr11 = TargetJvmVersion.TARGET_JVM_VERSION_ATTRIBUTE.name to "11"
+    val targetJvmAttr8 = TargetJvmVersion.TARGET_JVM_VERSION_ATTRIBUTE.name to "8"
 
     projectScriptPath.appendText(
       """
@@ -118,6 +119,17 @@ class PublishingTest : BasePluginTest() {
     publish()
     // sourceCompatibility doesn't affect the target JVM version.
     assertions(attrsWithoutTargetJvm + targetJvmAttr11)
+
+    projectScriptPath.appendText(
+      """
+        tasks.named('compileJava') {
+          options.release = 8
+        }
+      """.trimIndent() + System.lineSeparator(),
+    )
+    publish()
+    // options.release flag is honored.
+    assertions(attrsWithoutTargetJvm + targetJvmAttr8)
   }
 
   @Test

src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowJavaPlugin.kt

@@ -75,9 +75,12 @@ public abstract class ShadowJavaPlugin @Inject constructor(
           objects.named(LibraryElements::class.java, LibraryElements.JAR),
         )
         attr.attribute(Bundling.BUNDLING_ATTRIBUTE, objects.named(Bundling::class.java, Bundling.SHADOWED))
-        val targetJvmVersion = provider {
-          javaPluginExtension.targetCompatibility.majorVersion.toInt()
-        }
+        val targetJvmVersion = configurations.named(JavaPlugin.COMPILE_CLASSPATH_CONFIGURATION_NAME)
+          .map { compileClasspath ->
+            compileClasspath.attributes.getAttribute(TargetJvmVersion.TARGET_JVM_VERSION_ATTRIBUTE)
+              ?: javaPluginExtension.targetCompatibility.majorVersion.toInt()
+          }
+
         // Track JavaPluginExtension to update targetJvmVersion when it changes.
         attr.attributeProvider(TargetJvmVersion.TARGET_JVM_VERSION_ATTRIBUTE, targetJvmVersion)
       }