An
ActionException with a custom message for the user.
Exception thrown if requested transition is invalid for this
target/operator The message string should be presented as an error
message to the operator. Normally you should try to pick up invalid input at the form validation
stage but in rare cases a problem can become apparent when the action is run.
This should only be used when there are
no data-base modifications to be rolled-back. If roll-back is required use the
sub-class
FatalTransitionException.
If you want the message shown as a form-error (so the form can be re-submitted)
then use a
TransitionValidationException.
