Protobuf has merged https://github.com/golang/protobuf/tree/dev into master on the 30th of april which will cause problems to anyone using protobuf generated code to encode data to bson.

https://groups.google.com/forum/#!topic/protobuf/N-elvFu4dFM

Specifically, they added 3 new fields to all generated structs

```

XXX_NoUnkeyedLiteral struct{}        `json:"-""`

XXX_unrecognized     []byte          `json:"-""`

XXX_sizecache        int32           `json:"-"`

```

The fix is to manually add a `bson:"-"` tag, however this breaks any CI that auto-regenerates protobuf on compilation.

If the `bson` encoder supported reading the json tags it would work seamlessly.