EDIT

import javax.inject.Named;

import org.eclipse.e4.ui.model.application.ui.basic.MPart;

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

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

import org.eclipse.jface.viewers.IStructuredSelection;

import eu.etaxonomy.cdm.api.service.IDescriptiveDataSetService;

import eu.etaxonomy.cdm.model.description.DescriptiveDataSet;

import eu.etaxonomy.cdm.model.description.TaxonDescription;

import eu.etaxonomy.cdm.persistence.dto.TaxonNodeDto;

import eu.etaxonomy.taxeditor.editor.descriptiveDataSet.matrix.CharacterMatrixPart;

import eu.etaxonomy.taxeditor.store.CdmStore;

        //FIXME #7957 Use actual marker type when implemented

        return MarkerType.TO_BE_CHECKED();

    }

    @Override

    public boolean canExecute(@Named(IServiceConstants.ACTIVE_PART)MPart activePart,

            MHandledMenuItem menuItem){

        boolean canExecute = super.canExecute(activePart, menuItem);

        if(canExecute){

            CharacterMatrixPart matrixPart = (CharacterMatrixPart) activePart.getObject();

            DescriptiveDataSet descriptiveDataSet = matrixPart.getDescriptiveDataSet();

            IStructuredSelection selection = ((CharacterMatrixPart)activePart.getObject()).getSelection();

            TaxonNodeDto taxonNodeDto = (TaxonNodeDto) selection.getFirstElement();

            TaxonDescription defaultTaxonDescription = CdmStore.getService(IDescriptiveDataSetService.class)

                    .findTaxonDescriptionByMarkerType(descriptiveDataSet.getUuid(), taxonNodeDto.getUuid(), getMarkerType());

            canExecute = defaultTaxonDescription==null;

            menuItem.setVisible(canExecute);

        }

        return canExecute;