docs: protected BinaryExpression findNotInstanceOfReturnExpression(IfStatement ifElse) {
          Statement elseBlock = ifElse.getElseBlock();
          if (!(elseBlock instanceof EmptyStatement)) {
              return null;
          }
          Expression conditionExpression = ifElse.getBooleanExpression().getExpression();
          if (!(conditionExpression instanceof BinaryExpression)) {
              return null;
          }
          BinaryExpression instanceOfExpression = (BinaryExpression) conditionExpression;
          int op = instanceOfExpression.getOperation().getType();
          if (op != Types.COMPARE_NOT_INSTANCEOF) {
              return null;
          }
          if (notReturningBlock(ifElse.getIfBlock())) {
              return null;
          }
          return instanceOfExpression;
      }