docs: @SuppressWarnings("rawtypes")
      private void synchronousInvokeCallback(Callable call) {
  
          Future future = streamingSlopResults.submit(call);
  
          try {
              future.get();
  
          } catch(InterruptedException e1) {
  
              logger.error("Callback failed", e1);
              throw new VoldemortException("Callback failed");
  
          } catch(ExecutionException e1) {
  
              logger.error("Callback failed during execution", e1);
              throw new VoldemortException("Callback failed during execution");
          }
  
      }