code: public GitlabCommitComparison compareCommits(Serializable projectId, String commitHash1, String commitHash2, Pagination pagination) throws IOException {
          String tailUrl = GitlabProject.URL + "/" + sanitizeProjectId(projectId) + GitlabCommitComparison.URL;
          Query query = new Query()
                  .append("from", commitHash1)
                  .append("to", commitHash2);
          query.mergeWith(pagination.asQuery());
          return retrieve().to(tailUrl + query, GitlabCommitComparison.class);
      }
docs: GET /projects/:id/repository/compare