code: @Override
      public final SourceDocument findByRootAndString(
              final RootDocument rootDocument, final String string) {
          final SourceDocument sourceDocument =
                  findByFileAndString(rootDocument.getFilename(), string);
          if (sourceDocument == null) {
              return null;
          }
          final Source source = sourceDocument.getGedObject();
          source.setParent(rootDocument.getGedObject());
          return sourceDocument;
      }
docs: {@inheritDoc}