message: dubbo_proxy: annotating a fall-through
  Fixes broken-internal build.
  Risk Level: Low (annotation change)
  Testing: tests now build using internal bazel
  Docs Changes: n/a
  Release Notes: n/a
diff: @@ -62,6 +62,7 @@ RpcResultPtr HessianDeserializerImpl::deserializeRpcResult(Buffer::Instance& buf
  case RpcResponseType::ResponseWithValue:
  case RpcResponseType::ResponseWithNullValue:
  has_value = false;
  + FALLTHRU;
  case RpcResponseType::ResponseValueWithAttachments:
  case RpcResponseType::ResponseNullValueWithAttachments:
  result = std::make_unique<RpcResultImpl>();
  