When keep a private property of a mutable data holder but exposing an immutable, is there a functional difference between

private val _listOfStrings = mutableListOf<String>()
val listOfStrings : List<String> = _listOfStrings
// and 
private val _listOfStrings = mutableListOf<String>()
val listOfStrings : List<String> 
    get() = _listOfStrings

Which one is better convention? I like how the first one is more concise but examples often show the second

The first example creates two (private) fields in the class, both pointing to the same object. It then generates a getter for the

listOfStrings

field. The second example creates one (private) field and a getter.

Ahhh that makes sense. 2 creates a property with no backing field, while 1 creates a second field pointing to the same reference. Thanks!

Correct

Just because you return

List<String>

doesn't make it immutable. Anyone can just perform

listOfStrings is MutableList<String>

to smart cast it as mutable. You would need to protect it if you truly need read-only guarantees (unless they do reflection to bypass it).

val listOfStrings = object : List<String> by _listOfStrings {}