https://DevOpsCloud.io -- Cloud Monk Losang Jinpa, Ph.D., MCSE/MCT, GitOps DevOps Engineer

Java HashSet.addAll() is a method in the Java HashSet class that adds all elements from a specified collection to the set. If any of the elements are already present, they are ignored, ensuring that only unique elements remain. Introduced in Java 1995 with Java 1.2, addAll() is widely used to merge collections or add multiple elements to a set in a single operation.

https://docs.oracle.com/javase/8/docs/api/java/util/HashSet.html