Form key not working, probably due to erroneous 'activiti' namespace

A form key set in the properties of a start event or user task in the Eclipse modeler does not trigger the form to be presented. Inversely, a form key set in the Modeler App does work, but does not show in the properties view when the model is viewed in the Eclipse modeler.

Looking at the XML, the likely cause is that the Eclipse modeler (incorrectly) places the formKey attribute in the `activity` namespace, defined as `xmlns:activiti="http://activiti.org/bpmn"`:

```xml

```

whereas the Modeler App puts it in the `flowable` namespace which is defined as `xmlns:flowable="http://flowable.org/bpmn"`:

```xml

```