src/properties/class-papi-property-flexible.php
protected function get_json_id( $key, $extra = '' ) {
		return $this->get_slug() . '_' . papi_slugify( $key ) . ( empty( $extra ) ? '' : '_' . $extra );
	}
protected function get_json_id( $key, $extra = '' ) {
		return $this->get_slug() . '_' . papi_slugify( $key ) . ( empty( $extra ) ? '' : '_' . $extra );
	}
Generate layout slug.

@param  string $key
@param  string $extra

@return string