Submit and save PDF forms to a custom destination

override fun onDocumentLoaded(document: PdfDocument) {
    super.onDocumentLoaded(document)
    ...
    // Retrieve the form field to include in the submit form action.
    val checkBoxField = document?.formProvider?.getFormFieldWithFullyQualifiedName("checkboxfield-1")

    val rectFPushButtonFormConfiguration = RectF(30f, 350f, 120f, 260f)
    val colorBitmap = Bitmap.createBitmap(500, 300, Bitmap.Config.ARGB_8888)
    val canvas = Canvas(colorBitmap)
    // Just use a red fill so the button is visible.
    canvas.drawColor(Color.RED)

    // Create the button form element (annotation).
    val pushButtonFormConfiguration = PushButtonFormConfiguration.Builder(
        0,
        rectFPushButtonFormConfiguration,
        colorBitmap
        )
            // Create the action and set the submission format to XFDF.
            .setAction(SubmitFormAction(
                "https://example.com/wherever-you-want-to-send-the-form",
                mutableListOf(checkBoxField),
                EnumSet.of(SubmitFormAction.SubmitFormActionFlag.XFDF)))
            .build()

    // Ask PSPDFKit to create the form field and add it to the document. This will also add the form element to the document.
    // The `fullyQualifiedName` must not be the same as an existing form field, but otherwise can be whatever you like.
    document?.formProvider?.addFormElementToPage("pushbuttonfield-1", pushButtonFormConfiguration)

@UiThread
@Override
public void onDocumentLoaded(@NonNull final PdfDocument document) {
    super.onDocumentLoaded(document);
    ...
    // Retrieve the form field to include in the submit form action.
    CheckBoxField checkBoxField = document.getFormProvider().getFormFieldWithFullyQualifiedName("checkboxfield-1");

    RectF rectFPushButtonFormConfiguration = new RectF(30f, 350f, 120f, 260f);
    Bitmap colorBitmap = Bitmap.createBitmap(500, 300, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(colorBitmap);
    // Just use a red fill so the button is visible.
    canvas.drawColor(Color.RED);

    // Create the button form element (annotation).
    PushButtonFormConfiguration pushButtonFormConfiguration = new PushButtonFormConfiguration.Builder(
        0,
        rectFPushButtonFormConfiguration,
        colorBitmap
        )
            // Create the action and set the submission format to XFDF.
            .setAction(new SubmitFormAction(
                "https://example.com/wherever-you-want-to-send-the-form",
                mutableListOf(checkBoxField),
                EnumSet.of(SubmitFormAction.SubmitFormActionFlag.XFDF)))
            .build();

    // Ask PSPDFKit to create the form field and add it to the document. This will also add the form element to the document.
    // The `fullyQualifiedName` must not be the same as an existing form field, but otherwise can be whatever you like.
    document.getFormProvider().addFormElementToPage("pushbuttonfield-1", pushButtonFormConfiguration);