private void removeSessionData(String sessionid, String from) {
        sessions.remove(sessionid);
        sessionsCounter.computeIfPresent(from, (key, count) -> {
            if (count.decrementAndGet() <= 0) {
                // Remove the AtomicInteger when no commands are being executed
                return null;
            } else {
                return count;
            }
        });
    }
Releases the data kept for the command execution whose id is sessionid. The number of
commands executions currently being executed by the user (full JID) will be decreased.

@param sessionid id of the session that identifies this command execution.
@param from the full JID of the command requester.
xmppserver/src/main/java/org/jivesoftware/openfire/commands/AdHocCommandManager.java