Using custom properties in mustache template

Description

I need to be able to use properties defined in .json file in while generating the client for swift4

Swagger-codegen version

3.0.19

Command line used for generation

swagger-codegen generate -i api.json -l swift4 -c config.json -t MustacheFiles

Steps to reproduce

In my api.json file I added a field like this -> { "myVar" : "SomeText" }
And in api.mustache file for swift4 I'm trying to use that variable by calling {{myVar}}, I have tried to use several different options but couldn't manage to reach that variable while generating.

Is there a way or a special command for defining custom variables to be used in these templates while using swagger-codegen?

I really need help in this. Please suggest me a solution

Start with the documented generation command using api.json, config.json, the swift4 generator, and the custom MustacheFiles template directory. Determine whether properties added to api.json are exposed to api.mustache during generation, and verify the result by generating the Swift client and checking whether the custom value appears in the output.