minor refactor on feed item method calls

Author: mateusjatenee

src/FeedItem.php

@@ -59,10 +59,7 @@ public function build()
     {
         return array_filter(
             $this->flatMap($this->acceptedProperties, function ($property) {
-
-                $method = $this->getMethodForProperty($property);
-
-                return [$property => $this->$method()];
+                return [$property => $this->getValueForProperty($property)];
             })
         );
     }

src/Traits/itemGetters.php

@@ -93,6 +93,15 @@ public function getMethodForProperty($method)
         return $this->getMethodsMap()[$method] ?? null;
     }
 
+    public function getValueForProperty($property)
+    {
+        if ($method = $this->getMethodForProperty($property)) {
+            return $this->$method();
+        }
+
+        return null;
+    }
+
     public function call($method)
     {
         return method_exists($this->object, $method) ? $this->object->$method() : null;