createColorPickerField example

private function createBasicFieldSet(): FieldSet
    {
        $attributes = array_merge($this->fieldSetDefaults, ['height' => 130]);
        $fieldSet = $this->createFieldSet(
            'basic_field_set',
            '__responsive_tab_general_fieldset_base__',
            ['attributes' => $attributes]
        );

        $fieldSet->addElement(
            $this->createColorPickerField(
                'brand-primary',
                '@brand-primary',
                $this->themeColorDefaults['brand-primary']
            )
        );
        $fieldSet->addElement(
            $this->createColorPickerField(
                'brand-primary-light',
                '@brand-primary-light',
                $this->themeColorDefaults['brand-primary-light']
            )
        );