bp_rest_register_field( string $component_id, string $attribute, array $args = array(), string $object_type = '' )

function bp_rest_register_field( $component_id, $attribute, $args = array(), $object_type = '' ) {
	$registered_fields = false;

	if ( ! $component_id || ! bp_is_active( $component_id ) || ! $attribute ) {
		return $registered_fields;
	}

	// Use the `bp_` prefix as we're using a WordPress global used for Post Types.
	$field_name = 'bp_' . $component_id;

	// Use the meta type as a suffix for the field name.
	if ( 'xprofile' === $component_id ) {
		if ( ! in_array( $object_type, array( 'data', 'field', 'group' ), true ) ) {
			return $registered_fields;
		}

		$field_name .= '_' . $object_type;
	}

	$args = bp_parse_args(
		$args,
		array(
			'get_callback'    => null,
			'update_callback' => null,
			'schema'          => null,
		),
		'rest_register_field'
	);

	// Register the field.
	register_rest_field( $field_name, $attribute, $args );

	if ( isset( $GLOBALS['wp_rest_additional_fields'][ $field_name ] ) ) {
		$registered_fields = $GLOBALS['wp_rest_additional_fields'][ $field_name ];
	}

	// Check it has been registered.
	return isset( $registered_fields[ $attribute ] );
}