Steps to reproduce:

1. Go to http://localhost:8080/magnoliaAuthor/.magnolia/admincentral#app:pages:detail;/demo-features/special-templates:edit
2. Add teaser RSS Combined Feed Paragraph.

   Caused by: java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.String
   	at info.magnolia.ui.form.field.factory.SelectFieldFactory.createDefaultValue(SelectFieldFactory.java:251)
   	at info.magnolia.ui.form.field.factory.AbstractFieldFactory.setPropertyDataSourceDefaultValue(AbstractFieldFactory.java:150)
   	at info.magnolia.ui.form.field.factory.SelectFieldFactory.setPropertyDataSourceAndDefaultValue(SelectFieldFactory.java:229)
   	at info.magnolia.ui.form.field.factory.AbstractFieldFactory.createField(AbstractFieldFactory.java:112)
   	at info.magnolia.ui.dialog.formdialog.FormBuilder.buildReducedForm(FormBuilder.java:165)
   	at info.magnolia.ui.dialog.formdialog.FormBuilder.buildForm(FormBuilder.java:106)
   	at info.magnolia.ui.dialog.formdialog.FormDialogPresenterImpl.buildView(FormDialogPresenterImpl.java:131)
   	at info.magnolia.ui.dialog.formdialog.FormDialogPresenterImpl.start(FormDialogPresenterImpl.java:115)
   	at info.magnolia.ui.dialog.formdialog.FormDialogPresenterImpl.start(FormDialogPresenterImpl.java:91)
   	at info.magnolia.pages.app.action.CreateComponentAction.openDialog(CreateComponentAction.java:139)
   	at info.magnolia.pages.app.action.CreateComponentAction.access$200(CreateComponentAction.java:82)
   	at info.magnolia.pages.app.action.CreateComponentAction$ComponentCreationCallback.onSuccess(CreateComponentAction.java:221)
   	at info.magnolia.ui.dialog.action.CallbackDialogAction.execute(CallbackDialogAction.java:58)
   	at info.magnolia.ui.api.action.AbstractActionExecutor.execute(AbstractActionExecutor.java:74)
   	... 112 more