[Feature] Add new relation query method to Eloquent adapter

Closes #490

Author: lindyhopchris

CHANGELOG.md

@@ -9,6 +9,8 @@ All notable changes to this project will be documented in this file. This projec
 
 - [#586](https://github.com/cloudcreativity/laravel-json-api/pull/586) Added French translations for validation and
   specification compliance messages.
+- [#490](https://github.com/cloudcreativity/laravel-json-api/issues/490) Add `newRelationQuery()` method to Eloquent
+  adapter.
 
 ### Fixed
 - [#576](https://github.com/cloudcreativity/laravel-json-api/issues/576) Correctly pass existing resource values to

src/Eloquent/AbstractAdapter.php

@@ -139,7 +139,7 @@ public function query(EncodingParametersInterface $parameters)
     public function queryToMany($relation, EncodingParametersInterface $parameters)
     {
         $this->applyScopes(
-            $query = $relation->newQuery()
+            $query = $this->newRelationQuery($relation)
         );
 
         return $this->queryAllOrOne(
@@ -161,7 +161,7 @@ public function queryToMany($relation, EncodingParametersInterface $parameters)
     public function queryToOne($relation, EncodingParametersInterface $parameters)
     {
         $this->applyScopes(
-            $query = $relation->newQuery()
+            $query = $this->newRelationQuery($relation)
         );
 
         return $this->queryOne(
@@ -286,6 +286,15 @@ protected function newQuery()
         return $builder;
     }
 
+    /**
+     * @param Relations\BelongsToMany|Relations\HasMany|Relations\HasManyThrough|Builder $relation
+     * @return Builder
+     */
+    protected function newRelationQuery($relation)
+    {
+        return $relation->newQuery();
+    }
+
     /**
      * @param $resourceId
      * @return Builder
@@ -699,7 +708,7 @@ protected function getQueryParameters(EncodingParametersInterface $parameters)
      */
     private function guessRelation()
     {
-        list($one, $two, $caller) = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 3);
+        [$one, $two, $caller] = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 3);
 
         return $this->modelRelationForField($caller['function']);
     }