Stripping out json metadata in the queue messages except for the ones… (#973)

* Stripping out json metadata in the queue messages except for the ones java is expecting

* coding standards

src/EventGenerator/EventGenerator.php

@@ -147,8 +147,19 @@ class EventGenerator implements EventGeneratorInterface {
       }
     }
 
-    unset($data["event"]);
-    unset($data["queue"]);
+    $allowed_keys = [
+      "file_upload_uri",
+      "fedora_uri",
+      "source_uri",
+      "destination_uri",
+      "args",
+      "mimetype",
+      "source_field",
+    ];
+    $keys_to_unset = array_diff(array_keys($data), $allowed_keys);
+    foreach ($keys_to_unset as $key) {
+      unset($data[$key]);
+    }
 
     if (!empty($data)) {
       $event["attachment"] = [