protected final void setOffendingState(int offendingState) {
		this.offendingState = offendingState;
	}
Get the ATN state number the parser was in at the time the error
occurred. For {@link NoViableAltException} and
{@link LexerNoViableAltException} exceptions, this is the
{@link DecisionState} number. For others, it is the state whose outgoing
edge we couldn't match.

<p>If the state number is not known, this method returns -1.</p>
runtime/Java/src/org/antlr/v4/runtime/RecognitionException.java