code: private CompletableFuture<Long> apply(InitializeEntry entry) {
      // Iterate through all the server sessions and reset timestamps. This ensures that sessions do not
      // timeout during leadership changes or shortly thereafter.
      long timestamp = executor.timestamp(entry.getTimestamp());
      for (ServerSessionContext session : executor.context().sessions().sessions.values()) {
        session.setTimestamp(timestamp);
      }
      log.release(entry.getIndex());
      return Futures.completedFutureAsync(entry.getIndex(), ThreadContext.currentContextOrThrow().executor());
    }
docs: Applies an initialize entry to the state machine.
  <p>
  Initialize entries are committed by leaders at the start of their term. Typically, no-op entries
  serve as a mechanism to allow leaders to commit entries from prior terms. However, we extend
  the functionality of the no-op entry to use it as an indicator that a leadership change occurred.
  In order to ensure timeouts do not expire during lengthy leadership changes, we use no-op entries
  to reset timeouts for client sessions and server heartbeats.