\begin{tikzpicture}
\umlemptyclass{A1}
\umlemptyclass[x=4, y=-1]{A2}
\umlemptyclass[y=-2]{A3}
\umlassoc[geometry=-|-, name=assoc]{A1}{A2}
\umluniaggreg[geometry=-|-, weight=0.3]{A3}{A2}
\umlpoint{assoc-4}
\end{tikzpicture}