yii\db\ActiveQuery::buildJoinWith PHP Method

    private function buildJoinWith()
    {
        $join = $this->join;
        $this->join = [];
        $model = new $this->modelClass();
        foreach ($this->joinWith as $config) {
            list($with, $eagerLoading, $joinType) = $config;
            $this->joinWithRelations($model, $with, $joinType);
            if (is_array($eagerLoading)) {
                foreach ($with as $name => $callback) {
                    if (is_int($name)) {
                        if (!in_array($callback, $eagerLoading, true)) {
                            unset($with[$name]);
                        }
                    } elseif (!in_array($name, $eagerLoading, true)) {
                        unset($with[$name]);
                    }
                }
            } elseif (!$eagerLoading) {
                $with = [];
            }
            $this->with($with);
        }
        // remove duplicated joins added by joinWithRelations that may be added
        // e.g. when joining a relation and a via relation at the same time
        $uniqueJoins = [];
        foreach ($this->join as $j) {
            $uniqueJoins[serialize($j)] = $j;
        }
        $this->join = array_values($uniqueJoins);
        if (!empty($join)) {
            // append explicit join to joinWith()
            // https://github.com/yiisoft/yii2/issues/2880
            $this->join = empty($this->join) ? $join : array_merge($this->join, $join);
        }
    }