When constructing component in Java it is initially in detached state (not attached to page).
If tooltip is being set to such detached component, it will be registered using it's
ANNONYMOUS UUID. Therefore popup will not show up at client side.

P.S. I have managed to overcome this issue by posting event to component being assembled
and setting tooltip in event listener, which naturally will happen lately in execution,
when all components are already in attached state and proper UUID is generated.