About Diffraction on m4/3s

Is everyone here aware of diffraction when shooting with m4/3s at a small aperture. I don't know if diffraction has occured in my pic above or not. How to tell and are they any indications of the diffraction so that I can avoid in the future. Of course I'm looking for the sharpest possible. What would be the ideal aperture? f8? f11? or maybe m4/3 need not be that small. Maybe an f5.6 is sufficient. My lens used in the pancake 17mm f2.8.

Thxs,

JAKOP