WordPress at a glance
filter is not described

woocommerce_rest_api_get_rest_namespaces filter-hook . WC 1.0

Get API namespaces - new namespaces should be registered here.

Usage

add_filter( 'woocommerce_rest_api_get_rest_namespaces', 'filter_function_name_8407' );
function filter_function_name_8407( $array ){
	// filter...

	return $array;
}
$array
-

Where the hook is called

Server::get_rest_namespaces()
woocommerce_rest_api_get_rest_namespaces
woocommerce/includes/rest-api/Server.php 52-59
return apply_filters(
	'woocommerce_rest_api_get_rest_namespaces',
	array(
		'wc/v1' => $this->get_v1_controllers(),
		'wc/v2' => $this->get_v2_controllers(),
		'wc/v3' => $this->get_v3_controllers(),
	)
);

Where in WP core the hook is used WooCommerce

woocommerce/includes/wccom-site/class-wc-wccom-site.php 30
add_action( 'woocommerce_rest_api_get_rest_namespaces', array( __CLASS__, 'register_rest_namespace' ) );