Documentation does not clearly provide any limits to where conditions on Transitions can be used, but the Fork Node doesn't support Transition conditions. For instance

<fork name='FORK_1' >
<transition name='t1' to='NODE_A'>
<condition>#

{false}</condition>
</transition>
<transition name='t2' to='NODE_B'/>
</fork>

will fail with a "transition condition #{false}

evaluated to 'false'" error when the fork attempts to take transition 't1'. Why provide for this? Someone might want to:

<fork name='FORK_1' >
<transition name='startMyProject' to='...'/>
<transition name='orderEngine to='...'>
<condition>#

{needsEngine}

</condition>
</transition>
<transition name='orderWheels to='...'>
<condition>#

{needsWheels}

</condition>
</transition>
...etc...
</fork>

Correcting the issue is as simple as making the following change to org.jbpm.graph.node.Fork.java:

// BRITT --replace the following line with the code below
// to check conditions before adding valid transitions...
//transitionNames = getLeavingTransitionsMap().keySet(); //original line

Iterator iter = leavingTransitions.iterator();
while (iter.hasNext()) {
Transition candidate = (Transition) iter.next();

String conditionExpression = candidate.getCondition();
if (conditionExpression != null) {
Object result = JbpmExpressionEvaluator.evaluate(conditionExpression, executionContext);
if (Boolean.TRUE.equals(result))

{ transitionNames.add(candidate.getName()); }

}else

{ transitionNames.add(candidate.getName()); }

}
if (transitionNames.size() == 0)

{ transitionNames.add(this.getDefaultLeavingTransition().getName()); this.getDefaultLeavingTransition().removeConditionEnforcement(); log.warn("All transition conditions have evaluated to 'false'. Taking the default transition."); }

// --BRITT