code: private void warnAboutNamespaceRedefinition(Name nameObj, Ref ref) {
      compiler.report(
          JSError.make(ref.getNode(), NAMESPACE_REDEFINED_WARNING, nameObj.getFullName()));
    }
docs: Reports a warning because a namespace was redefined.
  
  @param nameObj A namespace that is being redefined
  @param ref The reference that set the namespace