code: @Override
      public void addTrait(String guid, String traitInstanceDefinition) throws AtlasException {
          guid                    = ParamChecker.notEmpty(guid, "entity id");
          traitInstanceDefinition = ParamChecker.notEmpty(traitInstanceDefinition, "trait instance definition");
  
          ITypedStruct traitInstance = deserializeTraitInstance(traitInstanceDefinition);
          addTrait(guid, traitInstance);
      }
docs: Adds a new trait to an existing entity represented by a guid.
  
  @param guid                    globally unique identifier for the entity
  @param traitInstanceDefinition trait instance json that needs to be added to entity
  @throws AtlasException