code: public TimeStats estimateTime(Object projectIdOrPath, Integer issueIid, Duration duration) throws GitLabApiException {
  
          if (issueIid == null) {
              throw new RuntimeException("issue IID cannot be null");
          }
  
          String durationString = (duration != null ? DurationUtils.toString(duration.getSeconds(), false) : null);
          GitLabApiForm formData = new GitLabApiForm().withParam("duration", durationString, true);
  
          Response response = post(Response.Status.OK, formData.asMap(),
                  "projects", getProjectIdOrPath(projectIdOrPath), "issues", issueIid, "time_estimate");
          return (response.readEntity(TimeStats.class));
      }
docs: Sets an estimated time of work in this issue
  
  <pre><code>GitLab Endpoint: POST /projects/:id/issues/:issue_iid/time_estimate</code></pre>
  
  @param projectIdOrPath the project in the form of an Integer(ID), String(path), or Project instance
  @param issueIid the internal ID of a project's issue
  @param duration set the estimate of time to this duration
  @return a TimeSTats instance
  @throws GitLabApiException if any exception occurs