Fix handling of effect value

Author: const-cloudinary

src/Transformation/Qualifier/QualifierValue/FullListExpressionQualifierMultiValue.php

@@ -29,11 +29,11 @@ class FullListExpressionQualifierMultiValue extends ListExpressionQualifierMulti
      */
     public function __toString()
     {
-        $value = parent::__toString();
-        if (StringUtils::contains($value, static::VALUE_DELIMITER)) {
-            return '(' . $value . ')';
+        $string = parent::__toString();
+        if (!empty($string)) {
+            return '(' . $string . ')';
         }
 
-        return $value;
+        return $string;
     }
 }

tests/Unit/Transformation/Common/EffectTest.php

@@ -301,6 +301,11 @@ public function testBackgroundRemoval()
             (string)Effect::backgroundRemoval()->fineEdges(false)
         );
 
+        self::assertEquals(
+            'e_background_removal:fineedges_y;hints_(cat)',
+            (string)Effect::backgroundRemoval()->fineEdges()->hints(ForegroundObject::cat())
+        );
+
         self::assertEquals(
             'e_background_removal:fineedges_y;hints_(cat;dog;bicycle)',
             (string)Effect::backgroundRemoval()->fineEdges()->hints(