Go to your Project Explorer Pane > Right click on your desired module/folder and add Rule.
Then configure your rule like:
In any microflow place a split and select ‘Rule’. Select your rule and pass in the desired string.
Rules are currently not supported in nanoflows.
The community commons has a standard Java function for that. Look for the functions IsEmptyString and IsNotEmptyString. You can use these functions in a split.