How to reset a Keycloak authentication flow and display a message or error message?

Question

Within a custom authentication flow SPI, you can reset the entire flow simply returning

context.resetFlow();

in e.g. an action method.

However, can you attach a message or attribute when resetting the flow, basically passing it into the Freemarker UI upon reset?

user_1154114 · Answer

context.forkWithErrorMessage(new FormMessage('label', 'Your error message here'));