CosmosMsg implementation

I am trying to add two different messages (with different types) to my contracts handle/execute-Response. For this I would like to introduce a new message, to be used with CosmosMsg::Custom to perform what previously was CosmosMsg::Wasm(WasmMsg::Execute.... I didn't find any documentation how the different CosmosMsg enums are processed. Is there a place where I can look this up?