Read-write list
Implement methods in ReadWriteList class so that multiple threads could read data at the same time
as long as there’s no thread that is updating the data. Only one thread can update the data at a time
causing other threads (both readers and writers) to block until the update is over.
Use ReadWriteLock implementation for this purpose.
In your solution you should lock and unlock read and write locks in order to fulfill
the conditions above.
Remember to use try-finally construct - you want to release the lock
even if the operation with the underlying list was not successful.
You can run main() to check your solution.