code: @Override
      public Collection<Person> findBySurname(final FinderObject owner,
              final String surname) {
          logger.info("Starting findBySurname");
          final List<Person> persons = new ArrayList<>();
          if (owner instanceof Root) {
              final Root root = (Root) owner;
              final RootDocumentMongo rootDocument =
                      (RootDocumentMongo) toDocConverter.createGedDocument(root);
              final Collection<PersonDocument> personDocuments =
                      repositoryManager.getPersonDocumentRepository()
                      .findByRootAndSurname(rootDocument, surname);
              for (final PersonDocument personDocument : personDocuments) {
                  persons.add(personDocument.getGedObject());
              }
          }
          logger.info("Ending findBySurname");
          return persons;
      }
docs: {@inheritDoc}