ContactUiState.kt

data class ContactUiState(
    val loading: Boolean = false,
    val contacts: GroupedContacts = Collections.emptyMap()
)

/**
* Type aliases provide alternative names for existing types. 
* If the type name is too long you can introduce a different shorter name 
* and use the new one instead. In this example, we've created a typealias 
* for `ContactModel` to convert it into a Map which includes the alphabets 
* as the key and the list of `ContactModel` as the values of the Map.
*/
typealias GroupedContacts = Map<String, List<ContactModel>>