code: public boolean addFeature(Feature feature) {
  		// Basic checks:
  		if (feature == null || layer == null || !feature.getLayer().getId().equals(layer.getId())) {
  			return false;
  		}
  
  		// Does feature already exist?
  		if (featureIds.contains(feature.getId())) {
  			return false;
  		}
  		featureIds.add(feature.getId());
  
  		// Feature checks out, add it to the grid:
  		ListGridRecord record = new ListGridRecord();
  		record.setAttribute(FIELD_NAME_FEATURE_ID, feature.getId());
  		copyToRecord(feature, record);
  		addData(record);
  		return true;
  	}
docs: Adds a new feature to the list. A {@link VectorLayer} must have been set first, and the feature must belong to
  that VectorLayer.
  
  @param feature
  The feature to be added to the list.
  @return Returns true in case of success, and false if the feature is already in the list or the feature is null
  or if the feature does not belong to the correct layer or if the layer has not yet been set.