WP_REST_Controller::get_fields_for_response

		if ( ! isset( $request['_fields'] ) ) {
			return $fields;
		}
		$requested_fields = wp_parse_list( $request['_fields'] );
		if ( 0 === count( $requested_fields ) ) {
			return $fields;
		}
		// Trim off outside whitespace from the comma delimited list.
		$requested_fields = array_map( 'trim', $requested_fields );
		// Always persist 'id', because it can be needed for add_additional_fields_to_object().
		if ( in_array( 'id', $fields, true ) ) {
			$requested_fields[] = 'id';
		}
		// Return the list of all requested fields which appear in the schema.
		return array_reduce(
			$requested_fields,
			function( $response_fields, $field ) use ( $fields ) {
				if ( in_array( $field, $fields, true ) ) {
					$response_fields[] = $field;
					return $response_fields;
				}
				// Check for nested fields if $field is not a direct match.
				$nested_fields = explode( '.', $field );
				// A nested field is included so long as its top-level property
				// is present in the schema.
				if ( in_array( $nested_fields[0], $fields, true ) ) {
					$response_fields[] = $field;
				}
				return $response_fields;
			},
			array()
		);
	}

	/**
	 * Retrieves an array of endpoint arguments from the item schema for the controller.
	 *
	 * @since 4.7.0
	 *
	 * @param string $method Optional. HTTP method of the request. The arguments for `CREATABLE` requests are
	 *                       checked for required values and may fall-back to a given default, this is not done
	 *                       on `EDITABLE` requests. Default WP_REST_Server::CREATABLE.
	 * @return array Endpoint arguments.
	 */
	public function get_endpoint_args_for_item_schema( $method = WP_REST_Server::CREATABLE ) {

		$schema                  = $this->get_item_schema();
		$schema_properties       = ! empty( $schema['properties'] ) ? $schema['properties'] : array();
		$endpoint_args           = array();
		$valid_schema_properties = array(
			'type',
			'format',
			'enum',
			'items',
			'properties',
			'additionalProperties',
			'minimum',
			'maximum',