@Override
	public Handle epsilon(GrammarAST node) {
		ATNState left = newState(node);
		ATNState right = newState(node);
		epsilon(left, right);
		node.atnState = left;
		return new Handle(left, right);
	}
From an empty alternative build {@code o-e->o}.
tool/src/org/antlr/v4/automata/ParserATNFactory.java