docs: @Override
      public AbstractPipelineOutput execute(final AbstractPipelineInput input) throws DITAOTException {
          final Collection<FileInfo> fis = job.getFileInfo(fi -> fi.isInput);
          if (!fis.isEmpty()) {
              final Map<URI, Map<String, Element>> mapSet = getMapMetadata(fis);
              pushMetadata(mapSet);
              pullTopicMetadata(input, fis);
          }
  
          return null;
      }