<objectContribution
            adaptable="true"
            objectClass="org.eclipse.core.resources.IFile"
            nameFilter="*.presto"
            id="br.com.spread.acceleo.presto.ui.popupMenus.contribution.IFile">

	private IField[] getSelectedFields(IStructuredSelection selection) {
		List elements= selection.toList();
		if (elements.size() > 0) {
			IField[] result= new IField[elements.size()];
			ICompilationUnit unit= null;
			for (int index= 0; index < elements.size(); index++) {
				if (elements.get(index) instanceof IField) {
					IField field= (IField) elements.get(index);

					if (index == 0) {
						// remember the CU of the first element
						unit= field.getCompilationUnit();
						if (unit == null) {
							return null;
						}
					} else if (!unit.equals(field.getCompilationUnit())) {
						// all fields must be in the same CU
						return null;
					}
					try {
						final IType type= field.getDeclaringType();
						if (type.isInterface() || type.isAnonymous()) {
							return null;
						}
					} catch (JavaModelException exception) {
						JavaPlugin.log(exception);
						return null;
					}

					result[index]= field;
				} else {
					return null;
				}
			}
			return result;
		}
		return null;
	}