Class com.google.common.util.concurrent.ListenableFutureTask

Change from non-final to final.

Added Methods
ListenableFutureTask<V> create(Runnable, V)	Creates a {@code ListenableFutureTask} that will upon running, execute the given {@code Runnable}, and arrange that {@code get} will return the given result on successful completion.
ListenableFutureTask<V> create(Callable<V>)	Creates a {@code ListenableFutureTask} that will upon running, execute the given {@code Callable}.