public void execute(ExecutionImpl execution) {
Activity activity = execution.getActivity();
String transitionName = null;
ScriptManager scriptManager = EnvironmentDefaults.getScriptManager();
Object result = scriptManager.evaluateExpression(expr, lang);
if ( (result!=null)
&& (! (result instanceof String))
) {
throw new JbpmException("expression '"+expr+"' in decision '"+activity.getName()+"' returned "+result.getClass().getName()+" instead of a transitionName (String): "+result);
}