Use fixed return variable name

[whalecold]

Is this a BUG REPORT or FEATURE REQUEST?:

Uncomment only one, leave it on its own line:

/kind bug

/kind feature

What happened:

When I use nirvana client to generate client for rpc server, it use the lower case strcut type name as return variable， it don't work when i use the native type such as int, string.

What you expected to happen:

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:

[whalecold]

/close