src/Relationship/HasManyRelationship.php
public function find($id)
    {
        $child = $this->childClassName;
        $model = $child::findWithParentId($id, $this->parent->getId());
        if ($model) {
            $model->setParent($this->parent);
        }
        return $model;
    }
public function find($id)
    {
        $child = $this->childClassName;
        $model = $child::findWithParentId($id, $this->parent->getId());
        if ($model) {
            $model->setParent($this->parent);
        }
        return $model;
    }
Find model by id.

@param mixed $id
@return ElasticsearchModel|null