code: @Override
      public final SubmissionDocument findByFileAndString(
              final String filename, final String string) {
          final Query searchQuery = new Query(Criteria.where("string").is(string)
                  .and("filename").is(filename));
          final SubmissionDocument submDocument = mongoTemplate
                  .findOne(searchQuery, SubmissionDocumentMongo.class);
          if (submDocument == null) {
              return null;
          }
          final Submission submission = (Submission) toObjConverter
                  .createGedObject(null, submDocument);
          submDocument.setGedObject(submission);
          return submDocument;
      }
docs: {@inheritDoc}