class FormTestCheckboxesRadiosForm

class FormTestCheckboxesRadiosForm extends FormBase {
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'form_test_checkboxes_radios';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state, $customize = FALSE) {
        // Expand #type checkboxes, setting custom element properties for some but not
        // all options.
        $form['checkboxes'] = [
            '#type' => 'checkboxes',
            '#title' => 'Checkboxes',
            '#options' => [
                0 => 'Zero',
                'foo' => 'Foo',
                1 => 'One',
                'bar' => $this->t('<em>Bar - checkboxes</em>'),
                '>' => "<em>Special Char</em><script>alert('checkboxes');</script>",
            ],
        ];
        if ($customize) {
            $form['checkboxes'] += [
                'foo' => [
                    '#description' => 'Enable to foo.',
                ],
                1 => [
                    '#weight' => 10,
                ],
            ];
        }
        // Expand #type radios, setting custom element properties for some but not
        // all options.
        $form['radios'] = [
            '#type' => 'radios',
            '#title' => 'Radios',
            '#options' => [
                0 => 'Zero',
                'foo' => 'Foo',
                1 => 'One',
                'bar' => '<em>Bar - radios</em>',
                '>' => "<em>Special Char</em><script>alert('radios');</script>",
            ],
        ];
        if ($customize) {
            $form['radios'] += [
                'foo' => [
                    '#description' => 'Enable to foo.',
                ],
                1 => [
                    '#weight' => 10,
                ],
            ];
        }
        $form['submit'] = [
            '#type' => 'submit',
            '#value' => 'Submit',
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $form_state->setResponse(new JsonResponse($form_state->getValues()));
    }

}