code: public <T> T writeLocked (@Nonnull final Supplier <? extends T> aSupplier)
    {
      writeLock ().lock ();
      try
      {
        return aSupplier.get ();
      }
      finally
      {
        writeLock ().unlock ();
      }
    }
docs: Execute the provided callable in a write lock. Note: no
  nullable/non-nullable can be assumed.
  
  @param aSupplier
  Callable to be executed. May not be <code>null</code>.
  @return The return value of the callable. May be <code>null</code>.
  @param <T>
  Return type