Integration tests require Java 8 due to reflection access

[headius]

There's at least one integration test that depends on making a core JDK method (Object.finalize) accessible. This prevents the integration tests from running on most recent versions of Java.

[INFO] Reactor Summary for Mavengem Protocol and Mavengem Wagon 2.0.4-SNAPSHOT:
[INFO] 
[INFO] Mavengem Protocol and Mavengem Wagon ............... SUCCESS [  0.442 s]
[INFO] Rubygems Tools ..................................... SUCCESS [ 39.098 s]
[INFO] Protocol Handler for Mavengem: ..................... SUCCESS [ 15.830 s]
[INFO] Mavengem Protocol Wagon ............................ FAILURE [  0.880 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  56.477 s
[INFO] Finished at: 2026-03-29T22:14:38-05:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-invoker-plugin:2.0.0:run (integration-test) on project mavengem-wagon: Execution integration-test of goal org.apache.maven.plugins:maven-invoker-plugin:2.0.0:run failed: An API incompatibility was encountered while executing org.apache.maven.plugins:maven-invoker-plugin:2.0.0:run: java.lang.ExceptionInInitializerError: null
[ERROR] -----------------------------------------------------
[ERROR] realm =    plugin>org.apache.maven.plugins:maven-invoker-plugin:2.0.0
[ERROR] strategy = org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy
[ERROR] urls[0] = file:/Users/headius/.m2/repository/org/apache/maven/plugins/maven-invoker-plugin/2.0.0/maven-invoker-plugin-2.0.0.jar
[ERROR] urls[1] = file:/Users/headius/.m2/repository/org/apache/maven/shared/maven-invoker/2.2/maven-invoker-2.2.jar
...
[ERROR] urls[46] = file:/Users/headius/.m2/repository/commons-io/commons-io/2.2/commons-io-2.2.jar
[ERROR] urls[47] = file:/Users/headius/.m2/repository/org/codehaus/plexus/plexus-interpolation/1.21/plexus-interpolation-1.21.jar
[ERROR] urls[48] = file:/Users/headius/.m2/repository/org/codehaus/plexus/plexus-i18n/1.0-beta-7/plexus-i18n-1.0-beta-7.jar
[ERROR] Number of foreign imports: 1
[ERROR] import: Entry[import  from realm ClassRealm[project>org.jruby.maven:mavengem:2.0.4-SNAPSHOT, parent: ClassRealm[maven.api, parent: null]]]
[ERROR] 
[ERROR] -----------------------------------------------------
[ERROR] : Unable to make protected void java.lang.Object.finalize() throws java.lang.Throwable accessible: module java.base does not "opens java.lang" to unnamed module @3d3a8c69
[ERROR] -> [Help 1]
[ERROR] 

If this test is still valid, it should be updated to avoid such reflection access when running on inaccessible Java versions.