Required really means that you need to store values in there.
Default only makes sense for the optional fields (because only in the
optional fields, it is possible to _not_ set a value, so in that case,
you get the default). That answers your question in which cases you
use defaults.
So sounds
Hi,
In my process of response message, if there is an error, the process would
be aborted and send back an error response message without filling the
required variables. To avoid the libpropobuf throws system exception for
missing required variables, I put the default values like following
