What´s that for? Memorial plaque for Gavrilo Princip

What does the Deutsches Historisches Museum have to do with the memorial plaque for Gavrilo Princip and the assassination in Sarajevo? This plaque, stolen by the National Socialists, was displayed during the Second World War in the Zeughaus in Berlin, Unter den Linden, as a war trophy until 1946, when it was returned to Yugoslavia. How this came about is described by the historian Michael Ilg in this article.