#JSON-RPC code generation contracts

• service, the semantic service shape ID.
• methods, the prepared MethodContract values, in lexical wire name order. Each contract has its operation and input IDs, parameter mode, explicit positional member order, method kind, result selection, active call reference, and application errors. An error has its exact code, data selection, and required data flag. Notification methods keep their kind in the contract.
• shapes, the service closure in lexical shape ID order. The closure includes member shapes. Resolve a member's target in the semantic model before you use a list or map element. Keep the service rename map when you choose symbols.
• values, the prepared structure policies and member names for parameters, results, and error data. Nested structures are included. A member has its semantic shape ID, wire name, required flag, and critical path separator.
• value_config, the effective value codec config. It keeps the member name mode for union tags, the default timestamp format, and the other value options.

///|
test {
  let loaded = @rpc.loader()
    .add_idl(
      "echo.smithy",
      (
        #|$version: "2"
        #|namespace example
        #|use smithy.rpc#jsonRpc
        #|use smithy.rpc#method
        #|@jsonRpc(versions: ["2.0"])
        #|service Echo { version: "1", operations: [EchoValue] }
        #|@method(name: "echo", params: "named", kind: "request")
        #|operation EchoValue { input: Input, output: Input }
        #|structure Input { @required text: String }
      ),
    )
    .assemble()
  let description = @jsonrpc.Description::for_service(
    loaded.model.unwrap(),
    @smithy.ShapeId::parse("example#Echo").unwrap(),
    @rpc.V2_0,
  )
  let peer = description.peer(@rpc.PeerName::parse("client").unwrap()).unwrap()
  assert_eq(peer.accepts, None)
  assert_eq(peer.calls.unwrap().methods[0].name.to_string(), "echo")
  assert_eq(peer.calls.unwrap().methods[0].kind, @rpc.RequestOnly)
}