Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

When using C-libcurl generator to generate kubernetes API, some field names are keywords of C programming language, e.g.

object_ *default;
list_t *enum;

And some field names include "-", e.g.

int x-kubernetes-int-or-string;

The source code fails to compile due to these field names.

openapi-generator version

master

OpenAPI declaration file content or url

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

Command line used for generation

mvn clean package
java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -i https://raw.githubusercontent.com/kubernetes/kubernetes/master/api/openapi-spec/swagger.json -g c -o ../c_k8s_api_client

Steps to reproduce

1. generate the c api client by the above command
2. check the file "c_k8s_api_client/model/v1_json_schema_props.h"

Related issues/PRs

#3970

Suggest a fix

does openapi-generator provide a method to escape the name of field in a struct ?