@Override
	public SqmNullnessPredicate visitIsNullPredicate(HqlParser.IsNullPredicateContext ctx) {
		parameterDeclarationContextStack.push( () -> true ); // allow multiple values for null checks
		try {
			final boolean negated = ctx.getChildCount() == 4;
			return new SqmNullnessPredicate(
					(SqmExpression<?>) ctx.getChild( 0 ).accept( this ),
					negated,
					creationContext.getNodeBuilder()
			);
		} finally {
			parameterDeclarationContextStack.pop();
		}
	}