Map<String,Any> vs Map<,

val data: MutableMap<String, Any>
/..../
val client = data.get("MY_DATA") as Map<String, Any>//Unchecked cast: Any? to Map<String, Any>

android studio suggest to convert it to

val client = data.get("MY_DATA") as *Map<*, *>*

What is difference between both?

Compiler thinks that your keys will have different type than String. Maybe an Int.