Fix configuration of the parameter type "content" in the Template configuration

Steps to reproduce:

1. In WebUI, navigate to Default Domain > Templates
2. create a File Template
3. after creation, go to the tab Template Configuration
4. click on the + button to add a parameter
5. in the popup, choose content for the Type
6. click on the Source field

Observe that nothing is displayed when trying to set the Source field

In JSF UI, there are 3 choices as it can be seen on the attached screenshot.

Expected behavior:

it should be possible to set a value for the content parameter type