The findbugs-maven-plugin and its dependencies must not be added to the classpath of the (forked) findbugs

[sewe]

The findbugs-maven-plugin puts itself and its transitive dependencies on the classpath of the (forked) FindBugs execution. This prevents any FindBugs plugin from using, say, commons-collection:commons-collection in a version incompatible with the one used by the findbugs-maven-plugin – which runs in a completely different JVM process!