Hide x-gitbook-* symbols in OpenAPI blocks (#2863)

packages/react-openapi/src/stringifyOpenAPI.ts

@@ -1,6 +1,17 @@
 /**
  * Stringify an OpenAPI object. Same API as JSON.stringify.
  */
-export function stringifyOpenAPI(body: unknown, transformer?: null, indent?: number): string {
-    return JSON.stringify(body, transformer, indent);
+export function stringifyOpenAPI(body: unknown, _?: null, indent?: number): string {
+    return JSON.stringify(
+        body,
+        (key, value) => {
+            // Ignore internal keys
+            if (key.startsWith('x-gitbook-')) {
+                return undefined;
+            }
+
+            return value;
+        },
+        indent,
+    );
 }