public void notifyErrorListeners(Token offendingToken, String msg,
									 RecognitionException e)
	{
		_syntaxErrors++;
		int line = -1;
		int charPositionInLine = -1;
		line = offendingToken.getLine();
		charPositionInLine = offendingToken.getCharPositionInLine();

		ANTLRErrorListener listener = getErrorListenerDispatch();
		listener.syntaxError(this, offendingToken, line, charPositionInLine, msg, e);
	}
Match needs to return the current input symbol, which gets put
 into the label for the associated token ref; e.g., x=ID.
runtime/Java/src/org/antlr/v4/runtime/Parser.java