code: ServerSessionContext registerResult(long sequence, ServerStateMachine.Result result) {
      results.put(sequence, result);
      return this;
    }
docs: Registers a session result.
  <p>
  Results are stored in memory on all servers in order to provide linearizable semantics. When a command
  is applied to the state machine, the command's return value is stored with the sequence number. Once the
  client acknowledges receipt of the command output the result will be cleared from memory.
  
  @param sequence The result sequence number.
  @param result The result.
  @return The server session.