Add space between class name and concat message (#4577)
Add space between class name and concat message (#4577)

The class name was linked to the next word in the sentence.
"User\UserRequestis not found in descriptor pool."
google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf