This bump changelist is applied a bit late with respect to the
1.6.0 branch cut. Look at the 1.6.0 to see the source of truth of
where it was cut. Do not assume it is the commit that precedes
this one.
It was not convenient to test in some scenarios without having a field in the message. All `SimpleResponse` messages were `equals` to each other. Users might not want to assume reference identity/inequality between server and client for equal/unequal messages even for InProcess. Even with reference identity, it would still be inconvenient if their were hundreds of messages.
To have a non-proto based String to String service instead is another solution, but the usefulness of this proto based service would still be too limited.
not necessary to synchronze every time calling
getServiceDescriptor(), if the descriptor has been created already;
go with the double-checked locking idom
GrpcServerRule configures an in-process server and channel. It is
useful for asserting requests being made to a service. A consumer can
create a mock implementation of their service that records each
request, then make assertions on those records in their test.