%\begin{tikzpicture}[scale=0.7,transform shape]
\begin{tikzpicture}[scale=1,transform shape]

  \begin{class}{Trace}{-5,0}
    \attribute{transfoName : String}
  \end{class}
  
  \begin{class}{TraceLink}{0,0}
    \attribute{ruleName : String}
  \end{class}
  
  \begin{class}{SourceElement}{4.5,1}
    \attribute{}
  \end{class}
 
  \begin{class}{TargetElement}{4.5,-1}
    \attribute{}
  \end{class}
  
  \composition{Trace}{links}{*}{TraceLink}
  \draw [umlcd style, ->] ([yshift=40pt]TraceLink) -- (SourceElement)
  node[near end, above,xshift=-12pt]{sources 1..*};
  %node[near end, above]{sources}
  %node[near end, below]{*};

\draw [umlcd style, ->] ([yshift=-40pt]TraceLink) -- (TargetElement)
  node[near end, below,xshift=-12pt]{targets 1..*};
%  node[near end, below]{targets}
%  node[near end, above]{*};
%controls +(-160:5em) and +(140:5em) ..

%  \unidirectionalAssociation{TraceLink}{sources}{*}{Element}
%  \unidirectionalAssociation{TraceLink}{targets}{*}{Element}
  
\end{tikzpicture}