public Set<Integer> getAltSet() {
		Set<Integer> alts = new HashSet<Integer>();
		if ( configs!=null ) {
			for (ATNConfig c : configs) {
				alts.add(c.alt);
			}
		}
		if ( alts.isEmpty() ) return null;
		return alts;
	}
Get the set of all alts mentioned by all ATN configurations in this
 DFA state.
runtime/Java/src/org/antlr/v4/runtime/dfa/DFAState.java