How to disable a button for input validation in FXML

Question

I have two fields: username and password. I want a button to remain disabled if these fields are blank or their length is less and n characters.

I tried using button disableProperty() in my controller but I want to do the validation in the FXML file. I don't know if it's possible or not.

My current validation:

    @FXML
    private TextField usernameField;
    @FXML
    private PasswordField passwordField;
    @FXML
    private Button signinButton;

    // Runs on initializing
    @Override
    protected void configure() {
        signinButton.disableProperty().bind(usernameField.textProperty().isEmpty()
                .or(usernameField.textProperty().length().lessThan(5))
                .or(passwordField.textProperty().isEmpty())
                .or(passwordField.textProperty().length().lessThan(4)));
    }

FXML file:

<TextField fx:id="usernameField" prefHeight="34.0" prefWidth="220.0" promptText="Username"/>
<PasswordField fx:id="passwordField" prefHeight="34.0" prefWidth="220.0" promptText="Password"/>
<Button fx:id="signinButton" mnemonicParsing="false" onAction="#onSignin" prefWidth="220.0" text="Sign in"/>

Thanks in advance!