code: public void register (int objectID, Object object) {
  		if (objectID == Integer.MAX_VALUE) throw new IllegalArgumentException("objectID cannot be Integer.MAX_VALUE.");
  		if (object == null) throw new IllegalArgumentException("object cannot be null.");
  		idToObject.put(objectID, object);
  		objectToID.put(object, objectID);
  		if (TRACE) trace("kryonet", "Object registered with ObjectSpace as " + objectID + ": " + object);
  	}
docs: Registers an object to allow the remote end of the ObjectSpace's connections to access it using the specified ID.
  <p>
  If a connection is added to multiple ObjectSpaces, the same object ID should not be registered in more than one of those
  ObjectSpaces.
  @param objectID Must not be Integer.MAX_VALUE.
  @see #getRemoteObject(Connection, int, Class...)