If you migrate models containing REST procedures from version 7.7.x the values for rest Method and URI do not display in designer 8.3. They are still in the xmi file but it seems the key names have changed. If I edit the xmi file and change the key names the values for the properties then show in the Designer.

key="rest:uri" is now key="REST:URI"
And
key="rest:restMethod" is now key="REST:METHOD"