google.protobuf.message.DecodeError when passed objects with nested levels above 30

まず、issue に示されているネストされた composite manifest で失敗を再現し、次に google.protobuf.message.DecodeError を報告する RunFunctionRequest のシリアライズとデコードを追跡します。深くネストされた入力値の処理を、記載されている成功した output-resource のケースと比較します。関数呼び出しが、示されたネストをそのデコードエラーなしで受け入れれば完了です。

What happened?

We have composition that generates or consumes values with a high level of nested sub-values. (Those are CRDs that we are using with the Kubernetes Provider)
When going over 30 levels of imbrication the error below is raised

crossplane: error: cannot render composite resource: cannot run pipeline step "blueprint": rpc error: code = Unknown desc = Unexpected <class 'google.protobuf.message.DecodeError'>: Error parsing message with type 'apiextensions.fn.proto.v1.RunFunctionRequest'

How can we reproduce it?

`
apiVersion:  <APIVERSION>
kind: XCOMPO
metadata:
  name: <NAME>
spec:
  debug:
    level0:
      level1:
        level2:
          level3:
            level4:
              level5:
                level6:
                  level7:
                    level8:
                      level9:
                        level10:
                          level11:
                            level12:
                              level13:
                                level14:
                                  level15:
                                    level16:
                                      level17:
                                        level18:
                                          level19:
                                            level20:
                                              level21:
                                                level22:
                                                  level23:
                                                    level24:
                                                      level25:
                                                        level26:
                                                          level27:
                                                            level28:
                                                              level29:

Running ☝ this composite would faild if there is a level30 as child of level29.

Could this be linked to the limits set in Protobuf (https://github.com/protocolbuffers/protobuf/issues/6537) ?

Note: there is no issue when outputing resources with more than 30 levels. (ie: running something like

rsp.desired.resources["toto"].resource.update(resources)

Where resources has more than 30 levels.
It is only when the function is called with too many depth inputs that the exception is raised.

What environment did it happen in?

Function version:
0.6.0