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

  \begin{class}{VirtualRoot}{-5,0}
  \end{class}
  
  \begin{class}{Class}{0,0}
  \attribute{name : String}
  \end{class}
  
  \begin{class}{Attribute}{5,0}
    \attribute{name : String}
  \end{class}
  
  \composition{VirtualRoot}{children}{0..*}{Class}
  \unidirectionalAssociation{Class}{root}{1}{VirtualRoot}
  
  \composition{Class}{attributes}{0..*}{Attribute}
  \unidirectionalAssociation{Attribute}{type}{1}{Class}

  %\myassociationtwo{Class}{subclass}{0..*}{Class}{0..*}{superclass}{-1,-3}{1,-3} %{210}
  \myassociationthree{Class}{subclass}{0..*}{Class}{0..*}{superclass}{-0.8,-2.5}{0.8,-2.5} %{210}
  %\association{Class}{subclass}{0..*}{Class}{superclass}{0..1} %{210}

\end{tikzpicture}