A bit further into this.
I created a new Model with another 3 fields so Now I have 2 in my modeler. I do the same steps and in the Add fields by origin tab and now 3 fields are present.
I also modify my original model to contain 3 fields and I close/re-open the modeler and the fields in the original model are still missing.
Then my modeler doesn't show any models at all ...
Finally, I had to restart the server and now all my models are present, my 2 models once updated have the correct fields when added as data origins in my form.
So, if anyone knows the only open question if anyone knows is.
in the modeler if I choose the option "From Java Class" when I create the Form Data Origin and enter the class (including package) I have created in a jar in eclipse and then loaded into the repository I don't get ANY fields or model when I got to the "Add Fields by origin" tab, is this to be expected?