From 917b4fca77fc9ee81c8dc71d38043f54c4d98562 Mon Sep 17 00:00:00 2001
From: Richard Pringle <rpring9@gmail.com>
Date: Wed, 19 Aug 2020 10:24:20 -0400
Subject: [PATCH] Prevent mutation of default headers

---
 packages/grpc-js/src/server-call.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/grpc-js/src/server-call.ts b/packages/grpc-js/src/server-call.ts
index 82d88517..bdefa68a 100644
--- a/packages/grpc-js/src/server-call.ts
+++ b/packages/grpc-js/src/server-call.ts
@@ -413,7 +413,7 @@ export class Http2ServerCallStream<
     this.metadataSent = true;
     const custom = customMetadata ? customMetadata.toHttp2Headers() : null;
     // TODO(cjihrig): Include compression headers.
-    const headers = Object.assign(defaultResponseHeaders, custom);
+    const headers = Object.assign({}, defaultResponseHeaders, custom);
     this.stream.respond(headers, defaultResponseOptions);
   }