public void dumpDeadEndConfigs(NoViableAltException nvae) {
		System.err.println("dead end configs: ");
		for (ATNConfig c : nvae.getDeadEndConfigs()) {
			String trans = "no edges";
			if ( c.state.getNumberOfTransitions()>0 ) {
				Transition t = c.state.transition(0);
				if ( t instanceof AtomTransition) {
					AtomTransition at = (AtomTransition)t;
					trans = "Atom "+getTokenName(at.label);
				}
				else if ( t instanceof SetTransition ) {
					SetTransition st = (SetTransition)t;
					boolean not = st instanceof NotSetTransition;
					trans = (not?"~":"")+"Set "+st.set.toString();
				}
			}
			System.err.println(c.toString(parser, true)+":"+trans);
		}
	}
Used for debugging in adaptivePredict around execATN but I cut
 it out for clarity now that alg. works well. We can leave this
 "dead" code for a bit.
runtime/Java/src/org/antlr/v4/runtime/atn/ParserATNSimulator.java