[BUG][KOTLIN] Kotlin client unescaped string template

[andrewemery]

Description

Property names that include a dollar sign are being interpreted by Kotlin as a string template.

openapi-generator version

4.1.3

OpenAPI declaration file content or url

definitions:
  '$special[model.name]':
    properties:
      '$special[property.name]':
        type: integer
        format: int64

Expected:

@SerialName(value = "\$special[property.name]") 

Actual:

@SerialName(value = "$special[property.name]") 

Command line used for generation

openapi-generator generate -g kotlin

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[lemoinem]

I'm not sure the fix for this issue addresses it properly.
We override the templates because we need some custom behavior and instead of relying on requiredVars and optionalVars, we use vars directly.
Regardless, I think the fix should be applied to all vars rather than only a subset of them...

I'll prepare a PR to improve the original fix.