Camel returns the CamelCased name.
This was moved from the now deprecated github.com/golang/protobuf/protoc-gen-go/generator package
If there is an interior underscore followed by a lower case letter, drop the underscore and convert the letter to upper case. There is a remote possibility of this rewrite causing a name collision, but it's so remote we're prepared to pretend it's nonexistent - since the C++ generator lowercases names, it's extremely unlikely to have two fields with different capitalizations. In short, _my_field_name_2 becomes XMyFieldName_2.