protected String escapeWSAndQuote(String s) {
//		if ( s==null ) return s;
		s = s.replace("\n","\\n");
		s = s.replace("\r","\\r");
		s = s.replace("\t","\\t");
		return "'"+s+"'";
	}
How should a token be displayed in an error message? The default
 is to display just the text, but during development you might
 want to have a lot of information spit out.  Override in that case
 to use t.toString() (which, for CommonToken, dumps everything about
 the token). This is better than forcing you to override a method in
 your token objects because you don't have to go modify your lexer
 so that it creates a new Java type.
runtime/Java/src/org/antlr/v4/runtime/DefaultErrorStrategy.java