The project was not built due to "Resource already exists on disk" errors in eclipse

If it can help… here’s one stack trace:

java.lang.Exception: Resource already exists on disk: '/someproject/bin/test/log4j2.properties'.
	at org.eclipse.core.internal.resources.ResourceException.provideStackTrace(ResourceException.java:42)
	at org.eclipse.core.internal.resources.ResourceException.<init>(ResourceException.java:38)
	at org.eclipse.core.internal.localstore.FileSystemResourceManager.copy(FileSystemResourceManager.java:329)
	at org.eclipse.core.internal.resources.Resource.copy(Resource.java:539)
	at org.eclipse.jdt.internal.core.builder.AbstractImageBuilder.copyResource(AbstractImageBuilder.java:401)
	at org.eclipse.jdt.internal.core.builder.BatchImageBuilder$3.visit(BatchImageBuilder.java:259)
	at org.eclipse.core.internal.resources.Resource.lambda$0(Resource.java:85)
	at org.eclipse.core.internal.watson.ElementTreeIterator.doIteration(ElementTreeIterator.java:85)
	at org.eclipse.core.internal.watson.ElementTreeIterator.doIteration(ElementTreeIterator.java:90)
	at org.eclipse.core.internal.watson.ElementTreeIterator.iterate(ElementTreeIterator.java:135)
	at org.eclipse.core.internal.resources.Resource.accept(Resource.java:94)
	at org.eclipse.core.internal.resources.Resource.accept(Resource.java:55)
	at org.eclipse.jdt.internal.core.builder.BatchImageBuilder.copyExtraResourcesBack(BatchImageBuilder.java:227)
	at org.eclipse.jdt.internal.core.builder.BatchImageBuilder.cleanOutputFolders(BatchImageBuilder.java:148)
	at org.eclipse.jdt.internal.core.builder.BatchImageBuilder.build(BatchImageBuilder.java:65)
	at org.eclipse.jdt.internal.core.builder.JavaBuilder.buildAll(JavaBuilder.java:278)
	at org.eclipse.jdt.internal.core.builder.JavaBuilder.build(JavaBuilder.java:192)
	at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:833)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:220)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:263)
	at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:316)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:319)
	at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:371)
	at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:392)
	at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:154)
	at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:244)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)