Loading various 3d objects to Java

Hi everyone!
How to load 3D models with different extensions in Java (specifically from Artec Studio 15)?
This forum post answered this question, but jme3 only supports the 2 file extensions I need to load (namely .obj and .fbx).  How can I load 3D models in PLY/STL/STEP formats in this case? I've googled 3d online converters that can change the file extensions, but I'm not sure if that's a good solution.
I'm not very familiar with the whole 3D subject, it's a customer request. Can anyone suggest in which direction I should look for an answer?
Best regards

Sorry if this is a bit late, but I have used Java 3D in the past, and I thought it was pretty good.  I believe it supports the loading of 3D object files.  Not sure if it supports the specific kinds of files you need, though.