[Kotlin] Enum deserialization not working

Description

When deserializing a response, if enums are used, and the enum value doesn't match with the enum name, an exception is thrown by moshi stating that the enum doesn't match expected values.

E.g.:

status: {
  type: "string",
  description: "Order Status",
  enum: [
    "Placed",
    "Approved",
    "Delivered"
  ]
}

When deserializing, it fails with: expected one of [placed, approved, delivered] but was Placed at path $.status

This happens because moshi's EnumJsonAdapter doesn't use the enum's getValue and instead either uses a Json annotation or name().

Swagger-codegen version

2.3.1

Command line used for generation

swagger-codegen generate -l kotlin -i swagger.yaml -o tmp

Steps to reproduce

Change on Petstore swagger spec any enum from lowercase to capitalized.

Suggest a fix/enhancement

A solution would be to add the Json annotation to each enum value. Another one to override the name method to return the value instead. One more is to provide a EnumJsonAdapter to moshi that can correctly decode the generated enums.

Start with the Kotlin output produced by swagger-codegen generate -l kotlin -i swagger.yaml -o tmp, using the Petstore specification with an enum changed to capitalized values. Compare the generated enum handling with Moshi's EnumJsonAdapter behavior. Done means the generated client deserializes those enum values without the expected-values exception.