...
Worthy of note, you can switch to server-side storage of user sessions (essentially similar to the V2 default) by setting the idp.session.StorageService property to shibboleth.StorageService, or an alternative defined by you. See StorageConfiguration for details.
The most important property to note, and the only one that MUST be set is the idp.authn.flows property. This is a regular expression that identifies the flows defined in general-authn.xml to enable. The expression applies only to the suffix of each flow ID (omitting the authn/ prefix), and the simplest way to express this is with a pipe (|) separated list of the flow names, e.g., flow1|flow2|flow3
...