diff --git a/plugins/woocommerce-blocks/src/Domain/Services/ExtendRestApi.php b/plugins/woocommerce-blocks/src/Domain/Services/ExtendRestApi.php
index 54466bedd84..f0d04e71288 100644
--- a/plugins/woocommerce-blocks/src/Domain/Services/ExtendRestApi.php
+++ b/plugins/woocommerce-blocks/src/Domain/Services/ExtendRestApi.php
@@ -44,36 +44,40 @@ class ExtendRestApi {
 	/**
 	 * An endpoint that validates registration method call
 	 *
-	 * @param string   $endpoint The endpoint to extend.
-	 * @param string   $namespace Plugin namespace.
-	 * @param callable $schema_callback Callback executed to add schema data.
-	 * @param callable $data_callback Callback executed to add endpoint data.
+	 * @param array $args {
+	 *     An array of elements that make up a post to update or insert.
+	 *
+	 *     @type string   $endpoint The endpoint to extend.
+	 *     @type string   $namespace Plugin namespace.
+	 *     @type callable $schema_callback Callback executed to add schema data.
+	 *     @type callable $data_callback Callback executed to add endpoint data.
+	 * }
 	 *
 	 * @throws Exception On failure to register.
 	 * @return boolean True on success.
 	 */
-	public function register_endpoint_data( $endpoint, $namespace, $schema_callback, $data_callback ) {
-		if ( ! is_string( $namespace ) ) {
+	public function register_endpoint_data( $args ) {
+		if ( ! is_string( $args['namespace'] ) ) {
 			$this->throw_exception( 'You must provide a plugin namespace when extending a Store REST endpoint.' );
 		}
 
-		if ( ! is_string( $endpoint ) || ! in_array( $endpoint, $this->endpoints, true ) ) {
+		if ( ! is_string( $args['endpoint'] ) || ! in_array( $args['endpoint'], $this->endpoints, true ) ) {
 			$this->throw_exception(
-				sprintf( 'You must provide a valid Store REST endpoint to extend, valid endpoints are: %1$s. You provided %2$s.', implode( ', ', $this->endpoints ), $endpoint )
+				sprintf( 'You must provide a valid Store REST endpoint to extend, valid endpoints are: %1$s. You provided %2$s.', implode( ', ', $this->endpoints ), $args['endpoint'] )
 			);
 		}
 
-		if ( ! is_callable( $schema_callback ) ) {
+		if ( ! is_callable( $args['schema_callback'] ) ) {
 			$this->throw_exception( '$schema_callback must be a callable function.' );
 		}
 
-		if ( ! is_callable( $data_callback ) ) {
+		if ( ! is_callable( $args['data_callback'] ) ) {
 			$this->throw_exception( '$data_callback must be a callable function.' );
 		}
 
-		$this->extend_data[ $endpoint ][ $namespace ] = [
-			'schema_callback' => $schema_callback,
-			'data_callback'   => $data_callback,
+		$this->extend_data[ $args['endpoint'] ][ $args['namespace'] ] = [
+			'schema_callback' => $args['schema_callback'],
+			'data_callback'   => $args['data_callback'],
 		];
 
 		return true;
@@ -177,7 +181,7 @@ class ExtendRestApi {
 		return [
 			/* translators: %s: extension namespace */
 			'description' => sprintf( __( 'Extension data registered by %s', 'woo-gutenberg-products-block' ), $namespace ),
-			'type'        => 'object',
+			'type'        => [ 'object', 'null' ],
 			'context'     => [ 'view', 'edit' ],
 			'readonly'    => true,
 			'properties'  => $schema,