Merge lists with addAll(..)

List<MyClass> mergedList = new ArrayList<>();
mergedList.addAll(list1);
mergedList.addAll(list2);
mergedList.addAll(list3);

Merge lists in Java 8

List<MyClass> mergedList = Stream.of(list1, list2, list3)
				 .flatMap(item -> item.stream())
				 .collect(Collectors.toList());

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