Missing document for "grand" messages or enums (inner messages with embedding level more than 2)

I have a temp.proto like this:

message MessageA {
  optional ChildEnum type = 1;
  enum ChildEnum {
    TYPE_A = 1;
    TYPE_B = 2;
    TYPE_C = 3;
  }
}

message MessageB {
  repeated ChildMessage child = 1;
  message ChildMessage {
    optional string name = 1;
    optional GrandMessage content = 2;
    message GrandMessage {
      optional string sub_name = 1;
    }
    optional GrandEnum sub_type = 3;
    enum GrandEnum {
      TYPE_D = 1;
      TYPE_E = 2;
    }
  }
}

And I run command like /usr/local/bin/protoc --proto_path=./ --plugin=protoc-gen-doc=/root/gocode/bin/protoc-gen-doc --doc_out=markdown,temp.md:. temp.proto. In the output doc (either markdown or html), MessageB.ChildMessage.GrandEnum & MessageB.ChildMessage.GrandMessage is missing both in table of contents and in document body.

The output markdown of table of contents is like this (missing GrandMessage & GrandEnum):

## Table of Contents
- [temp.proto](#temp.proto)
    - [MessageA](#.MessageA)
    - [MessageB](#.MessageB)
    - [MessageB.ChildMessage](#.MessageB.ChildMessage)
    - [MessageA.ChildEnum](#.MessageA.ChildEnum)
- [Scalar Value Types](#scalar-value-types)

It seems to me that the recursive level (embedded level) is limited to < 3 when parsing inner messages / enums, is there any concern of infinite loop or something? Can this limitation be customized by input param? Thanks!

pseudomuto / protoc-gen-doc

Missing document for "grand" messages or enums (inner messages with embedding level more than 2) #360