Source

File: wp-includes/rest-api.php

function rest_validate_request_arg( $value, $request, $param ) {
	$attributes = $request->get_attributes();
	if ( ! isset( $attributes['args'][ $param ] ) || ! is_array( $attributes['args'][ $param ] ) ) {
		return true;
	}
	$args = $attributes['args'][ $param ];

	return rest_validate_value_from_schema( $value, $args, $param );
}