code: @Deprecated
    public synchronized long getNativeObjectId(T o) {
      checkNotNull(o);
      Long nativeId = nativeObjToIdMap.inverse().get(o);
      if (nativeId == null) {
        nativeId = nextId;
        if (debug) {
          System.out.printf("NativeObjRegistry %s: register %d -> %s%n", name, nativeId, o);
        }
        nativeObjToIdMap.put(nativeId, o);
        nextId++;
      }
      return nativeId;
    }
docs: Retrieve the native id for given object. Assigns a new unique id to the object if not
  previously registered.
  
  @deprecated Use {@link #register(Object)} instead.