## Feature Request ### Motivation Right now in pilota, when I wrote like this: ```thrift struct A { 1: required map<i32, string> m, } ``` It will generate: ```rust pub struct A { pub m: ::std::collections::HashMap<i32, ::pilota::FastStr>, } ``` And there is no other way to generate code like followings as `pilota.rust_type` annotation cannot work on container type. ```rust pub struct A { pub m: ::std::collections::HashMap<i32, String>, } ```