Rust codegen creates incorrectly escaped parameter names

Description

Generating Rust APIs for Kubernetes or any other API using parameters names which match keywords generates invalid rust since the escaped parameters names are invalid.

The swagger file contains "continue" as a parameter. This gets escaped by the codegen to “_continue”. Unfortunately this fails to compile when used in a format macro:

error: invalid format string: invalid argument name `_continue`
     --> kubernetes/src/client/mod.rs:21864:99
      |
21864 |         let query__continue = param__continue.map_or_else(String::new, |query| format!("continue={_continue}&", _continue=query.to_string()));
      |                                                                                                   ^^^^^^^^^ invalid argument name in format string
      |
      = note: argument names cannot start with an underscore

OpenAPI declaration file content or url

https://raw.githubusercontent.com/kubernetes/kubernetes/release-1.11/api/openapi-spec/swagger.json
https://raw.githubusercontent.com/kubernetes/kubernetes/master/api/swagger-spec/v1.json

Suggest a fix/enhancement

Could position, rather than parameter names, be used in the format string?

[wing328]

@nlj21 do you still need help with this issue? Please let me know.