To assist users in migrating from github.com/golang/protobuf
to google.golang.org/protobuf, make it such that functiionality like
proto.Marshal doesn't panic on nil interfaces.
Similar to how the new implementation treats a typed nil message
as an empty message, we treat a nil interface as being equivalent
to an "untyped" empty message.
Change-Id: Ic037f386f855b122f732b34d370e524b7c0d76f1
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/228837
Reviewed-by: Damien Neil <dneil@google.com>
An Is prefix implies it returns a boolean.
A Check prefix better suggests that it could return an error.
Change-Id: I6ffcb32099a944c656c07654c294a0980efb2d0e
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/220338
Reviewed-by: Damien Neil <dneil@google.com>