code: private Object addOrUpdateCollectionEntry(AtlasVertex instanceVertex, AttributeInfo attributeInfo,
                                                IDataType elementType, Object newAttributeValue, Object currentValue,
                                                String propertyName, Operation operation)
              throws AtlasException {
  
          switch (elementType.getTypeCategory()) {
          case PRIMITIVE:
          case ENUM:
              return newAttributeValue != null ? newAttributeValue : null;
  
          case ARRAY:
          case MAP:
          case TRAIT:
              // do nothing
              return null;
  
          case STRUCT:
          case CLASS:
              final String edgeLabel = GraphHelper.EDGE_LABEL_PREFIX + propertyName;
              return addOrUpdateReference(instanceVertex, attributeInfo, elementType, newAttributeValue, (AtlasEdge)currentValue,
                      edgeLabel, operation);
  
          default:
              throw new IllegalArgumentException("Unknown type category: " + elementType.getTypeCategory());
          }
      }
docs: ****************************************** ARRAY & MAP *************************************************