This error is triggered by a Javadoc @link tag that either is syntactically invalid or can't be resolved. See javadoc documentation for an explanation of how to correctly format the contents of this tag.
Use the erased type of method parameters in @link tags. For example, write {@link #foo(List)} instead of {@link #foo(List<Bah>)}. Javadoc does yet not support generics in @link tags, due to a bug: JDK-5096551.