Fix internal properties appearing in OpenAPI docs. (#2774)

packages/react-openapi/src/stringifyOpenAPI.ts

@@ -0,0 +1,20 @@
+import { SYMBOL_MARKDOWN_PARSED, SYMBOL_REF_RESOLVED } from './resolveOpenAPIPath';
+
+/**
+ * Stringify an OpenAPI object. Same API as JSON.stringify.
+ */
+export function stringifyOpenAPI(body: unknown, transformer?: null, indent?: number): string {
+    return JSON.stringify(
+        body,
+        (_key, value) => {
+            if (value && !Array.isArray(value) && typeof value === 'object') {
+                // Extract out internal keys used in parsing
+                const { [SYMBOL_MARKDOWN_PARSED]: _, [SYMBOL_REF_RESOLVED]: __, ...rest } = value;
+                return rest;
+            }
+
+            return value;
+        },
+        indent,
+    );
+}