code: @Override
      public void export(RDFHandler handler, Resource... contexts) throws RepositoryException, RDFHandlerException {
          exportStatements(null, null, null, true, handler);
      }
docs: exports statements via RDFHandler
  
  TBD- should refactor
  
  @param handler
  @param contexts
  @throws RepositoryException
  @throws RDFHandlerException