Extract setting mutated attribute into method

src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php

@@ -543,9 +543,7 @@ public function setAttribute($key, $value)
         // which simply lets the developers tweak the attribute as it is set on
         // the model, such as "json_encoding" an listing of data for storage.
         if ($this->hasSetMutator($key)) {
-            $method = 'set'.Str::studly($key).'Attribute';
-
-            return $this->{$method}($value);
+            return $this->setMutatedAttributeValue($key, $value);
         }
 
         // If an attribute is listed as a "date", we'll convert it from a DateTime
@@ -582,6 +580,18 @@ public function hasSetMutator($key)
         return method_exists($this, 'set'.Str::studly($key).'Attribute');
     }
 
+    /**
+     * Set the value of an attribute using its mutator.
+     *
+     * @param  string  $key
+     * @param  mixed  $value
+     * @return mixed
+     */
+    protected function setMutatedAttributeValue($key, $value)
+    {
+        return $this->{'set'.Str::studly($key).'Attribute'}($value);
+    }
+
     /**
      * Determine if the given attribute is a date or date castable.
      *