@Override
	public String getOptionString(String key) {
		if ( cmdLineOptions!=null && cmdLineOptions.containsKey(key) ) {
			return cmdLineOptions.get(key);
		}
		String value = super.getOptionString(key);
		if ( value==null ) {
			value = defaultOptions.get(key);
		}
		return value;
	}
Track stream used to create this tree
tool/src/org/antlr/v4/tool/ast/GrammarRootAST.java