Set<ID> getPendingRequestIDs(int theDSFID) {
    Set<ID> result = new HashSet<>();
    synchronized (viewRequests) {
      for (AbstractGMSMessage<ID> msg : viewRequests) {
        if (msg.getDSFID() == theDSFID) {
          result.add(((HasMemberID<ID>) msg).getMemberID());
        }
      }
    }
    return result;
  }
returns the member IDs of the pending requests having the given DataSerializableFixedID
geode-membership/src/main/java/org/apache/geode/distributed/internal/membership/gms/membership/GMSJoinLeave.java