docs: public String getDuplicateNameErrorMessage(IEObjectDescription description, EClass clusterType, EStructuralFeature feature) {
  		EObject object = description.getEObjectOrProxy();
  		String shortName = String.valueOf(feature != null ? object.eGet(feature) : "<unnamed>");
  		StringBuilder result = new StringBuilder(64);
  		result.append("Duplicate ");
  		result.append(getTypeLabel(clusterType));
  		result.append(" '");
  		result.append(shortName);
  		result.append("'");
  		if (isContainerInformationHelpful(description, shortName)) {
  			EObject container = getContainerForErrorMessage(object);
  			if (container != null) {
  				String containerTypeLabel = getTypeLabel(container.eClass());
  				EStructuralFeature containerNameFeature = getNameFeature(container);
  				if (isContainerInformationHelpful(description, container, containerTypeLabel, containerNameFeature)) {
  					result.append(" in ");
  					result.append(containerTypeLabel);
  					if (containerNameFeature != null) {
  						String containerName = String.valueOf(container.eGet(containerNameFeature));
  						if (containerName != null) {
  							result.append(" '");
  							result.append(containerName);
  							result.append("'");
  						}
  					}
  				}
  			} 
  		}
  		return result.toString();
  	}