Support parameter names of Queries/Mutations in DgsConstants

[e-wag]

Hello everyone,

the codegen plugin currently does not provide the parameter names defined in mutations/queries. It would be really nice to have parameter names available as well in the generated DgsConstants object as you could provide the constant to DataFetchingEnvironments getArgument() function instead of a string to retrieve the raw input values. Then we would get additional compiler validation if the parameter name should ever change & we wouldn't have to rely on mere strings or own constants.

Little background info: We are relying on the raw input values to validate if some nullable input fields are actually set by the client or just by default due to general object mapping.

I am thinking about something like this:

  public object MUTATION {
    public const val TYPE_NAME: String = "Mutation"
    
    public object UPDATEINPUT {
      public const val TYPE_NAME: String = "updateInput"
      public const val PARAMETER_INPUT: String = "input"
    }
  }

Could we add support for something like this? Or is there some way to retrieve the parameter names I am just unaware of?