fix: fix classpath error with surefire

[monperrus]

in some cases, surefire copies src/test/resources in target and hence considers binary classes as real ones and Bidon is not well located.

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.21.0:test (default-test) on project spoon-core: There are test failures.
[ERROR] 
[ERROR] Please refer to /home/martin/martin-no-backup/spoon/spoon-core/target/surefire-reports for the individual test results.
[ERROR] Please refer to dump files (if any exist) [date]-jvmRun[N].dump, [date].dumpstream and [date]-jvmRun[N].dumpstream.
[ERROR] There was an error in the forked process
[ERROR] annotated-parameter-on-nested-class-constructor/classes/Bidon (wrong name: Bidon)
[ERROR] org.apache.maven.surefire.booter.SurefireBooterForkException: There was an error in the forked process
[ERROR] annotated-parameter-on-nested-class-constructor/classes/Bidon (wrong name: Bidon)
[ERROR] 	at org.apache.maven.plugin.surefire.booterclient.ForkStarter.fork(ForkStarter.java:658)
[ERROR] 	at org.apache.maven.plugin.surefire.booterclient.ForkStarter.fork(ForkStarter.java:533)
[ERROR] 	at org.apache.maven.plugin.surefire.booterclient.ForkStarter.run(ForkStarter.java:278)
[ERROR] 	at org.apache.maven.plugin.surefire.booterclient.ForkStarter.run(ForkStarter.java:244)
[ERROR] 	at org.apache.maven.plugin.surefire.AbstractSurefireMojo.executeProvider(AbstractSurefireMojo.java:1149)
[ERROR] 	at org.apache.maven.plugin.surefire.AbstractSurefireMojo.executeAfterPreconditionsChecked(AbstractSurefireMojo.java:978)
[ERROR] 	at org.apache.maven.plugin.surefire.AbstractSurefireMojo.execute(AbstractSurefireMojo.java:854)
[ERROR] 	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
[ERROR] 	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210)
[ERROR] 	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156)
[ERROR] 	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148)
[ERROR] 	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
[ERROR] 	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
[ERROR] 	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
[ERROR] 	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
[ERROR] 	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
[ERROR] 	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
[ERROR] 	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
[ERROR] 	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:956)
[ERROR] 	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
[ERROR] 	at org.apache.maven.cli.MavenCli.main(MavenCli.java:192)
[ERROR] 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[ERROR] 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[ERROR] 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[ERROR] 	at java.lang.reflect.Method.invoke(Method.java:498)
[ERROR] 	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
[ERROR] 	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
[ERROR] 	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
[ERROR] 	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)
[ERROR]