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

Java ConcurrentHashMap.putIfAbsent() is a method in the Java ConcurrentHashMap class that inserts a key-value pair into the map only if the key is not already present. If the key already exists, it does nothing and returns the existing value. Introduced in Java 2014 with Java 8, putIfAbsent() is widely used in concurrent applications where you want to ensure that no overwriting happens in a thread-safe manner.

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