docs: public Milestone activateMilestone(Object projectIdOrPath, Integer milestoneId) throws GitLabApiException {
  
          if (milestoneId == null) {
              throw new RuntimeException("milestoneId cannot be null");
          }
  
          GitLabApiForm formData = new GitLabApiForm().withParam("state_event", MilestoneState.ACTIVATE);
          Response response = put(Response.Status.OK, formData.asMap(),
                  "projects", getProjectIdOrPath(projectIdOrPath), "milestones", milestoneId);
          return (response.readEntity(Milestone.class));
      }