code: private AtlasEdge addOrUpdateStruct(AtlasVertex instanceVertex, AttributeInfo attributeInfo,
              ITypedStruct newAttributeValue, AtlasEdge currentEdge,
              String edgeLabel, Operation operation) throws AtlasException {
          AtlasEdge newEdge = null;
          if (GraphHelper.elementExists(currentEdge) && newAttributeValue != null) {
              //update
              updateStructVertex(newAttributeValue, currentEdge, operation);
              newEdge = currentEdge;
          } else if (! GraphHelper.elementExists(currentEdge) && newAttributeValue != null) {
              //add
              newEdge = addStructVertex(newAttributeValue, instanceVertex, attributeInfo, edgeLabel);
          }
          return newEdge;
      }
docs: ****************************************** STRUCT *************************************************