code: public void onRetry(Throwable t) {
          try {
              this.retries++;
              debugRelativeTime("onRetry: " + this.retries);
              metricRecorder.incrementRetriesCount();
              if (timeout != null) {
                  timeout.restart();
                  attemptStartTime = System.nanoTime();
              }
              onAttemptComplete(t);
          } catch (RuntimeException e) {
              // Unchecked exceptions thrown here can be swallowed by Failsafe
              // This catch ensures we at least get an FFDC
              throw e;
          }
      }
docs: Called when we have determined that this execution is going to be retried
  
  @param t the Throwable that prompted the retry