code: public static void generateSessionIdIfNecessary(final TraceeBackend backend, final String sessionId) {
  		if (backend != null && !backend.containsKey(TraceeConstants.SESSION_ID_KEY) && backend.getConfiguration().shouldGenerateSessionId()) {
  			backend.put(TraceeConstants.SESSION_ID_KEY, Utilities.createAlphanumericHash(sessionId, backend.getConfiguration().generatedSessionIdLength()));
  		}
  	}
docs: Generate session id hash if it doesn't exist in TraceeBackend and configuration asks for one
  
  @param backend   Currently used TraceeBackend
  @param sessionId Current http sessionId