Camellia has alternate leaves. mystery plant has opposite/paired leaves, So it will ruled out Camellia sp
I do not know what plant is that, but do suspect a Privet (Ligustrum) especially Ligustrum lucidum, the glossy privet.
May be you could add pictures of whole tree, trunk/bark. if there are no blooms/fruit at the moment. Those additional image will help to make a better ID