rest_preload_api_request

 * @return mixed The stabilized value.
 */
function rest_stabilize_value( $value ) {
	if ( is_scalar( $value ) || is_null( $value ) ) {
		return $value;
	}

	if ( is_object( $value ) ) {
		_doing_it_wrong( __FUNCTION__, __( 'Cannot stabilize objects. Convert the object to an array first.' ), '5.5.0' );

		return $value;
	}

	ksort( $value );

	foreach ( $value as $k => $v ) {
		$value[ $k ] = rest_stabilize_value( $v );
	}

	return $value;
}

/**
 * Validate a value based on a schema.
 *
 * @since 4.7.0
 * @since 4.9.0 Support the "object" type.
 * @since 5.2.0 Support validating "additionalProperties" against a schema.
 * @since 5.3.0 Support multiple types.
 * @since 5.4.0 Convert an empty string to an empty object.
 * @since 5.5.0 Add the "uuid" and "hex-color" formats.
 *              Support the "minLength", "maxLength" and "pattern" keywords for strings.
 *              Support the "minItems", "maxItems" and "uniqueItems" keywords for arrays.
 *              Validate required properties.
 *
 * @param mixed  $value The value to validate.
 * @param array  $args  Schema array to use for validation.
 * @param string $param The parameter name, used in error messages.
 * @return true|WP_Error
 */
function rest_validate_value_from_schema( $value, $args, $param = '' ) {
	$allowed_types = array( 'array', 'object', 'string', 'number', 'integer', 'boolean', 'null' );

	if ( ! isset( $args['type'] ) ) {
		/* translators: 1. Parameter */
		_doing_it_wrong( __FUNCTION__, sprintf( __( 'The "type" schema keyword for %s is required.' ), $param ), '5.5.0' );
	}

	if ( is_array( $args['type'] ) ) {
		$best_type = rest_handle_multi_type_schema( $value, $args, $param );

		if ( ! $best_type ) {
			/* translators: 1: Parameter, 2: List of types. */
			return new WP_Error( 'rest_invalid_param', sprintf( __( '%1$s is not of type %2$s.' ), $param, implode( ',', $args['type'] ) ) );
		}

		$args['type'] = $best_type;
	}