EDIT

package eu.etaxonomy.taxeditor.handler.defaultHandler.e4;

import java.util.UUID;

import javax.inject.Named;

import org.eclipse.e4.core.contexts.IEclipseContext;

import org.eclipse.e4.core.di.annotations.CanExecute;

import org.eclipse.e4.core.di.annotations.Execute;

import org.eclipse.e4.ui.model.application.MApplication;

import org.eclipse.e4.ui.model.application.ui.menu.MHandledMenuItem;

import org.eclipse.e4.ui.services.IServiceConstants;

import org.eclipse.e4.ui.workbench.modeling.EModelService;

import org.eclipse.e4.ui.workbench.modeling.EPartService;

import org.eclipse.swt.widgets.Shell;

public abstract class DefaultOpenHandlerBaseE4 <T> {

    protected IEclipseContext context;

    protected MApplication application;

    protected EModelService modelService;

    @Execute

    public void execute(@Named(IServiceConstants.ACTIVE_SHELL)Shell shell, MHandledMenuItem menuItem,

            EModelService modelService, EPartService partService, MApplication application,

            IEclipseContext context) {

        this.context = context;

        this.modelService = modelService;

        this.application = application;

        String commandId = menuItem.getCommand().getElementId();

        Object transientData = menuItem.getTransientData().get(commandId+".uuid");

        if(transientData instanceof UUID){

            T entity = getEntity((UUID) transientData);

            open(entity, shell, partService);

        }

    }

    @CanExecute

    public boolean canExecute(MHandledMenuItem menuItem) {

        boolean canExecute = false;

        String commandId = menuItem.getCommand().getElementId();

        Object transientData = menuItem.getTransientData().get(commandId+".uuid");

        if(transientData instanceof UUID){

            T entity = getEntity((UUID) transientData);

            canExecute = canExecute(entity);

        }

        menuItem.setVisible(canExecute);

        return canExecute;

    }

    protected abstract T getEntity(UUID uuid);

    protected abstract void open(T entity, Shell shell, EPartService partService);

    protected abstract boolean canExecute(T entity);

}