Fixed form reset causing image uploads to fail when using Flex

CHANGELOG.md

@@ -10,6 +10,7 @@
 3. [](#bugfix)
     * Fixed `Folder::move()` throwing an error when target folder is changed by only appending characters to the end [#3445](https://github.com/getgrav/grav/issues/3445)
     * Fixed some phpstan issues (all code level 1, Framework level 3)
+    * Fixed form reset causing image uploads to fail when using Flex
 
 # v1.7.22
 ## 09/16/2021

system/src/Grav/Framework/Flex/FlexDirectoryForm.php

@@ -129,6 +129,17 @@ class FlexDirectoryForm implements FlexDirectoryFormInterface, JsonSerializable
         return $this;
     }
 
+    /**
+     * @param string $uniqueId
+     * @return void
+     */
+    public function setUniqueId(string $uniqueId): void
+    {
+        if ($uniqueId !== '') {
+            $this->uniqueid = $uniqueId;
+        }
+    }
+
     /**
      * @param string $name
      * @param mixed $default

system/src/Grav/Framework/Flex/FlexForm.php

@@ -172,6 +172,17 @@ class FlexForm implements FlexObjectFormInterface, JsonSerializable
         return $this;
     }
 
+    /**
+     * @param string $uniqueId
+     * @return void
+     */
+    public function setUniqueId(string $uniqueId): void
+    {
+        if ($uniqueId !== '') {
+            $this->uniqueid = $uniqueId;
+        }
+    }
+
     /**
      * @param string $name
      * @param mixed $default