@Override
		public boolean equals(ATNConfig a, ATNConfig b) {
			if ( a==b ) return true;
			if ( a==null || b==null ) return false;
			return a.state.stateNumber==b.state.stateNumber
				&& a.context.equals(b.context);
		}
The hash code is only a function of the {@link ATNState#stateNumber}
and {@link ATNConfig#context}.
runtime/Java/src/org/antlr/v4/runtime/atn/PredictionMode.java