What were they talking about? Mystery of a brief conversation between Duda and Tusk

A surprise meeting between Donald Tusk and Andrzej Duda at the General Assembly of the United Nations. They sat next to each other and exchanged a few words and now other politicians are speculating what could they have been talking about. Activists of Law and Justice and the opposition are commenting on Donald Trump's reference to Poland in his speech to world leaders at the U.N.