Convert an Object with List<String> to ImmutableList

Question

My Object :

List<Test>
.
.
.
Test {
String name;
String salary;
List<String> nickNames;}

I would like to convert this list to an ImmutableList (ie)

ImmutableList<Test>

where nickNames in Test must also be converted into an ImmuatableList

I could do something like this

listOfObjects()
.stream()
.map(obj -> {obj.setNickNames(ImmutableList.copyOf(obj.getNickNames)); return obj;})
.collect(ImmutableList.toImmutableList());

But is there any other cleaner way to achieve this ?