I would like to use a static image ( not a light probe ) in some kind of panoramic form like equirectangular or cube map, to simulate reflections on the surface of a mesh that also has regular textures. I don’t know if env mapping just something you specify in a Material Definition, or if you need to update things in code as the camera angle changes. A short, simple example would be wonderful 
Step 1: add a skybox
Step 2: generate a light probe from it
Step 3: set some over the top radius on the light probe
Step 4: import your level
Step 5: ???
Step 6: Profit!
There is another way which involves setting the env map to the good old Lighting.j3md shader, but I’m not sure how that works.
Generally you’ll get better advice if you describe the what you hope to achieve, rather than how you plan to achieve it.
From your post, I’m unclear on how the reflections and the regular textures are supposed to be combined.
SkyFactory loads cube maps. SimpleWaterProcessor simulates reflections. TestSimpleWater combines the two. Perhaps it will provide the example you seek:
jmonkeyengine/TestSimpleWater.java at v3.2 · jMonkeyEngine/jmonkeyengine · GitHub