src/Adapter/AbstractResourceAdapter.php
protected function fillRelationships(
        $record,
        Collection $relationships,
        EncodingParametersInterface $parameters
    ) {
        $relationships->filter(function ($value, $field) use ($record) {
            return $this->isFillableRelation($field, $record);
        })->each(function ($value, $field) use ($record, $parameters) {
            $this->fillRelationship($record, $field, $value, $parameters);
        });
    }
protected function fillRelationships(
        $record,
        Collection $relationships,
        EncodingParametersInterface $parameters
    ) {
        $relationships->filter(function ($value, $field) use ($record) {
            return $this->isFillableRelation($field, $record);
        })->each(function ($value, $field) use ($record, $parameters) {
            $this->fillRelationship($record, $field, $value, $parameters);
        });
    }
Fill relationships from a resource object.

@param $record
@param Collection $relationships
@param EncodingParametersInterface $parameters
@return void