Generic unknown keys object entity

js/entity/UnknownKeysEntity.js

@@ -0,0 +1,14 @@
+import IEntity from "./IEntity"
+import TypeInitialization from "./TypeInitialization"
+
+export default class UnknownKeysEntity extends IEntity {
+
+    static attributes = {
+        lookbehind: new TypeInitialization(String, false, "", false, true)
+    }
+
+    constructor(values = {}) {
+        super(values)
+        /** @type {String} */ this.lookbehind
+    }
+}