DiffRefs not populating for Merge Requests List

For my GitLab Plugin for Jenkins,

Raising this issue based on discussions here. The following API calls are made in Java using gitlab4j.

I need DiffRefs of Merge Request. Although DiffRefs get populated for single MergeRequest call e.g.

gitLabApi.getMergeRequestApi().getMergeRequest(projectpath, iid);

But it doesn't work when called for a list of Merge Requests. The DiffRefs field is returned null e.g.

for(final MergeRequest m : gitLabApi.getMergeRequestApi().getMergeRequests(projectpath, Constants.MergeRequestState.OPENED)) {
        System.out.println(m);
        System.out.println("-----------------");
    }

For getting the DiffRefs I need to perform an extra api call inside the for loop, e.g.

for(final MergeRequest m : gitLabApi.getMergeRequestApi().getMergeRequests(projectpath, Constants.MergeRequestState.OPENED)) {
        System.out.println(gitLabApi.getMergeRequestApi().getMergeRequest(project, m.getIid()));
        System.out.println("-----------------");
    }

But this might be a little resource intensive. Want to know if there is a reason why diffRefs are not populated when api calls for a list of MRs.

Thanks.