refactor: remove unneeded concrete common class

custom form fields creation logic as overridable function

react/common/src/ElixFormsComponentAbstract.tsx

@@ -86,7 +86,11 @@ export default abstract class ElixFormsComponentAbstract extends Component<IElix
     );
   }
 
-  public createCustomFormFields(callback: (formFieldFactory: IElixFormsComponentCustomFormFieldFactory) => JSX.Element = () => <></>): JSX.Element {
+  protected createCustomFormFields(formFieldFactory: IElixFormsComponentCustomFormFieldFactory): JSX.Element {
+    return <></>;
+  }
+
+  private renderCustomFormFields(): JSX.Element {
     const formFieldFactory = {
       createBooleanInput: (name: string, label: string, required: boolean = false) =>
         this.createBooleanInput(name, label, required),
@@ -106,7 +110,7 @@ export default abstract class ElixFormsComponentAbstract extends Component<IElix
         this.createTextAreaInput(name, label, required),
     };
 
-    return callback(formFieldFactory);
+    return this.createCustomFormFields(formFieldFactory);
   }
 
   public override render(): React.ReactElement<IElixFormsComponentProperties> {
@@ -116,8 +120,7 @@ export default abstract class ElixFormsComponentAbstract extends Component<IElix
       environmentMessage,
       hasTeamsContext,
       userDisplayName,
-      additionalFieldsJson,
-      customFormFieldsConfiguration
+      additionalFieldsJson
     } = this.props;
 
     const queryParams = new URLSearchParams(window.location.search);
@@ -130,7 +133,7 @@ export default abstract class ElixFormsComponentAbstract extends Component<IElix
         <form action="https://procedure.unipr.it/rwe2/ComeBackToElixAndSave" method="post" acceptCharset="ISO-8859-1">
           {this.createMandatoryFormFields(queryParams)}
           {this.createAdditionalFormFields()}
-          {this.createCustomFormFields(customFormFieldsConfiguration)}
+          {this.renderCustomFormFields()}
           <input type="submit" value="Submit"/>
         </form>
       </section>