code: public void resetCheckpoint() {
          synchronized (lock) {
              if (c4ReplStatus != null && c4ReplStatus
                  .getActivityLevel() != C4ReplicatorStatus.ActivityLevel.STOPPED) {
                  throw new IllegalStateException(
                      "Replicator is not stopped. Resetting checkpoint is only allowed when the replicator is in the "
                          + "stopped state.");
              }
              shouldResetCheckpoint = true;
          }
      }
docs: Resets the local checkpoint of the replicator, meaning that it will read all
  changes since the beginning of time from the remote database. This can only be
  called when the replicator is in a stopped state.