The basic problem is that conditions were allowed on all transitions, regardless of the type of node that the transitions were leaving.

However, neither the code nor the documentation was explicit enough about how conditional (also known as "guarded") transitions should be handled in a number of cases, most importantly the following:

• getting/determining the default transition from a node that is not a decision

Although it might be hard to imagine, this issue has, over time, lead to an increasing number of other issues that were a result of a policy regarding conditional transitions and non-decision nodes, that was not clear – in both the code and the documentation. It has also lead to a number of changes in the code in order to fix these issues, which were symptoms of the basic problem: no clear solution for handling conditions on transitions leaving non-decision nodes.

For the related problem in the designer, see JBIDE-8956.