@Override
	public Interval getSourceInterval() {
		if ( start == null ) {
			return Interval.INVALID;
		}
		if ( stop==null || stop.getTokenIndex()<start.getTokenIndex() ) {
			return Interval.of(start.getTokenIndex(), start.getTokenIndex()-1); // empty
		}
		return Interval.of(start.getTokenIndex(), stop.getTokenIndex());
	}
Override to make type more specific
runtime/Java/src/org/antlr/v4/runtime/ParserRuleContext.java