framework/db/conditions/ConjunctionConditionBuilder.php
private function buildExpressionsFrom(ExpressionInterface $condition, &$params = [])
    {
        $parts = [];
        foreach ($condition->getExpressions() as $condition) {
            if (is_array($condition)) {
                $condition = $this->queryBuilder->buildCondition($condition, $params);
            }
            if ($condition instanceof ExpressionInterface) {
                $condition = $this->queryBuilder->buildExpression($condition, $params);
            }
            if ($condition !== '') {
                $parts[] = $condition;
            }
        }

        return $parts;
    }
private function buildExpressionsFrom(ExpressionInterface $condition, &$params = [])
    {
        $parts = [];
        foreach ($condition->getExpressions() as $condition) {
            if (is_array($condition)) {
                $condition = $this->queryBuilder->buildCondition($condition, $params);
            }
            if ($condition instanceof ExpressionInterface) {
                $condition = $this->queryBuilder->buildExpression($condition, $params);
            }
            if ($condition !== '') {
                $parts[] = $condition;
            }
        }

        return $parts;
    }
Builds expressions, that are stored in $condition

@param ExpressionInterface|ConjunctionCondition $condition the expression to be built.
@param array $params the binding parameters.
@return string[]