code: public Pager<Milestone> getGroupMilestones(Object groupIdOrPath, int itemsPerPage) throws GitLabApiException {
          return (new Pager<Milestone>(this, Milestone.class, itemsPerPage, null,
                  "groups", getGroupIdOrPath(groupIdOrPath), "milestones"));
      }
docs: Get a Page of group milestones.
  
  @param groupIdOrPath the group in the form of an Integer(ID), String(path), or Group instance
  @param itemsPerPage The number of Milestone instances that will be fetched per page
  @return the milestones associated with the specified group
  @throws GitLabApiException if any exception occurs