You could make this backward compatible with a 

```
{BinObj, _EncodingMethod} = case Module:encode_handoff_item(K, V) of
                                              BinObj where is_binary(BinObj) ->
                                                 {BinObj, encode_zlib}; %% or whatever your default should be
                                              EncodedItem ->
                                                 EncodedItem
                                            end,
```

But perhaps this is part of a multi-step PR that I don't have full context on.