code: public static void generateInvocationIdIfNecessary(final TraceeBackend backend) {
  		if (backend != null && !backend.containsKey(TraceeConstants.INVOCATION_ID_KEY) && backend.getConfiguration().shouldGenerateInvocationId()) {
  			backend.put(TraceeConstants.INVOCATION_ID_KEY, Utilities.createRandomAlphanumeric(backend.getConfiguration().generatedInvocationIdLength()));
  		}
  	}
docs: Generate invocation id if it doesn't exist in TraceeBackend and configuration asks for one
  
  @param backend Currently used TraceeBackend