code: public synchronized ClassList getClassList() throws NotAllowedException
  	{
  		ClassList classes = new ClassList();
  		for (Object definition : getRootElementList())
  		{
  			if (definition instanceof SClassDefinition)
  				classes.add((SClassDefinition) definition);
  			else
  				throw new NotAllowedException("Other definition than ClassDefinition is found: "
  						+ definition.getClass().getName());
  		}
  		return classes;
  	}
docs: /*
  (non-Javadoc)
  @see org.overture.ide.core.ast.IVdmElement#getClassList()