public static ExecutorService unconfigurableExecutorService (ExecutorService executor)

Returns an object that delegates all defined ExecutorService methods to the given executor, but not any other methods that might otherwise be accessible using casts. This provides a way to safely "freeze" configuration and disallow tuning of a given concrete implementation.

Parameters:
executor    the underlying implementation

Returns:  an ExecutorService instance

Exceptions:
NullPointerException    if executor null