This is an extension of the gogoproto “protoc-gen-gogoslick” with
options for using time.Time for google.protobuf.Timestamp fields
and performing Go field name substitution using custom names.
These things are possible to do using normal gogo extensions, but then
we would litter the protobuf file with Go-specific options and
extensions, which not only feels like a bad thing to do, but also
would complicate things for non-Go consumers of the protobuf file.
use_std_time: use time.Time for google.protobuf.Timestamp
default_custom_names: use a set of custom names that turns common
acronyms and initialisms into uppercase (ID, UUID, URL, URI, HTTP).
custom_names=[filename.json]: specifies a file containing
additional custom names as a json objeect using the protobuf field
name as the key and the custom name as value. Protobuf field names
can be qualified with the message name Message.field and qualified
names take precedence over unqualified names.