code: public Registration readClass (Input input) {
  		if (input == null) throw new IllegalArgumentException("input cannot be null.");
  		try {
  			return classResolver.readClass(input);
  		} finally {
  			if (depth == 0 && autoReset) reset();
  		}
  	}
docs: Reads a class and returns its registration.
  @return May be null.
  @see ClassResolver#readClass(Input)