Set a default value for "defaultValue"?

Description

I'm trying to make a swagger client generator for C and I have noticed that when using the key "defaultValue" in my .mustache files and there is no defaultValue it gets set no "null". Is it possible to change that? I want it to be "NULL" and not "null".

Swagger-codegen version

2.4.0

Swagger declaration file content or url

My .mustache file:

{{#models}}{{#model}}
struct {{classname}} {
    {{#vars}}
    m_{{name}} = {{{defaultValue}}};
    {{/vars}}
}
{{/model}}{{/models}}

Command line used for generation

mvn package
java -DdebugModels -cp ../../modules/swagger-codegen-cli/target/swagger-codegen-cli.jar:target/C-swagger-codegen-1.0.0.jar io.swagger.codegen.Codegen -l C -i /home/nwerner/Projekte/datav2/framework/webapi/timeseries-rest-api-def.yaml -o ./test > test.txt

Steps to reproduce

Create a new swagger module and try to generate a client with at least one model, without defaultValue set, using your custom .mustache and the value will be "null". Can this be changed to be "NULL" instead?

char* m_{{name}} = {{{defaultValue}}}; -> char* m_{{name}} = null;

Suggest a fix/enhancement

I already searched in the repo and in the CodegenConfig class, but I couldn't locate how I could change it from "null" to "NULL".

Start with the custom .mustache template and trace how the defaultValue field is populated, including the CodegenConfig class mentioned in the issue. Use the provided mvn package and generation command to verify that an absent default renders as NULL for the C client without changing explicitly supplied values.