In Java, most implementations of Map interface provide a

constructor to create copy of another map. But the copy method is

not synchronized.

Therefore, when a thread is copying the map, another thread can

modify it.

To prevent such a scenario, we should use

Collections.synchronizedMap() method to first create a thread-safe

map.

Another way of to create a shallow copy is by using clone() method.

But it is not considered as a recommended approach

https://www.baeldung.com/java-copy-hashmap