Modifying DLP IncidentSeverity FlexResponse Plugin

I am trying to develop a FlexResponse plugin for DLP that will trigger on an event, and in that event I will grab the IncidentDetail to get the filename and other parameters I may need. After which I will do some lookups and the like. What I do need help with, is to figure out how to update incident details, the primary parameter I need to update is the IncidentSeverity. 

The FlexResponse API is very sparse in describing how to do so, and the API documentations mentions classes in the API that I lack (using 11.6). 

Simply I really just need to grab IncidentDetails and then modify the IncidentSeverity based on parameters of my own choosing.