Background

For optional literal, Java will generate an enum for it. For example, for below case, optionalLiteral will be generated as an enum named ModelOptionalLiteral.

model Model {
  literal: "literal";
  optionalLiteral?: "optionalLiteral";
}

alias Request = {
  @query
  literalParam: "literalParam";

  @query
  optionalLiteralParam?: "optionalLiteralParam";
};

@route("/literal")
interface LiteralOp {
  @put
  @route("/put")
  put(...Request, @body body: Model): Model;
}

Issue

But ModelOptionalLiteral is just a constant in TCGC which has no usage. But we will generate it as enum, so we need usage. When there is no usage, we will not generate the model, so after adopting TCGC, ModelOptionalLiteral is deleted.

Solution

TCGC provide usage and access for SdkConstantType, so that we can get the usage and access from TCGC.