code: public function build(ExpressionInterface $expression, array &$params = [])
      {
          $operator = $expression->getOperator();
          $query = $expression->getQuery();
  
          $sql = $this->queryBuilder->buildExpression($query, $params);
  
          return "$operator $sql";
      }
docs: Method builds the raw SQL from the $expression that will not be additionally
  escaped or quoted.
  
  @param ExpressionInterface|ExistsCondition $expression the expression to be built.
  @param array $params the binding parameters.
  @return string the raw SQL that will not be additionally escaped or quoted.