JDK26-Build 28 - Final field modelId in class org.apache.maven.api.model.InputSource has been mutated reflectively #11581
Description
Affected version
4.0.0-rc5
Bug description
Using Maven 4.0.0-rc5
$> mvn --version
Apache Maven 4.0.0-rc-5 (fb3ecaef88106acb40467a450248dfdbd75f3b35)
Maven home: /Users/khm/tools/maven
Java version: 26-ea, vendor: Oracle Corporation, runtime: /Users/khm/.sdkman/candidates/java/26.ea.28-open
Default locale: en_DE, platform encoding: UTF-8
OS name: "mac os x", version: "14.6.1", arch: "aarch64", family: "mac"
Using JDK 26-Build 28
Starting a project just with a simple:
$> mvn clean
[INFO]
[INFO] 1 problem was encountered while building the effective settings (use -e to see details)
[INFO]
[INFO] Scanning for projects...
WARNING: Final field modelId in class org.apache.maven.api.model.InputSource has been mutated reflectively by class org.apache.maven.impl.model.DefaultModelBuilder$ModelBuilderSessionState in unnamed module @7dcf94f8 (file:/Users/khm/tools/maven/lib/maven-impl-4.0.0-rc-5.jar)
WARNING: Use --enable-final-field-mutation=ALL-UNNAMED to avoid a warning
WARNING: Mutating final fields will be blocked in a future release unless final field mutation is enabled
[INFO] Inspecting build with total of 1 modules
[INFO] Installing Central Publishing features
[INFO]
[INFO] -----------------------------------< com.soebes.so.example.reflection:deep-reflection >-----------------------------------
[INFO] Building Deep Reflection 1.0-SNAPSHOT
[INFO] from pom.xml
[INFO] ---------------------------------------------------------[ jar ]----------------------------------------------------------
[INFO]
[INFO] --- clean:3.5.0:clean (default-clean) @ deep-reflection ---
[INFO] Deleting /Users/khm/ws-git-soebes/examples/deep-reflection/target
[INFO] --------------------------------------------------------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] --------------------------------------------------------------------------------------------------------------------------
[INFO] Total time: 0.415 s
[INFO] Finished at: 2025-12-21T10:34:41+01:00
[INFO] --------------------------------------------------------------------------------------------------------------------------
The WARNING is the result of JEP 500 which produces those things.
The culprit code (https://github.com/apache/maven/blob/maven-4.0.x/impl/maven-impl/src/main/java/org/apache/maven/impl/model/DefaultModelBuilder.java#L1505):
InputLocation loc = model.getLocation("");
InputSource v4src = loc != null ? loc.getSource() : null;
if (v4src != null) {
try {
Field field = InputSource.class.getDeclaredField("modelId");
field.setAccessible(true);
field.set(v4src, ModelProblemUtils.toId(model));
} catch (Throwable t) {
// TODO: use a lazy source ?
throw new IllegalStateException("Unable to set modelId on InputSource", t);
}
}It's using setAccessible on a class which itself is defined as final and also has not set Methods...