code: private void validateEntityAssociations(String guid, List<AtlasClassification> classifications) throws AtlasBaseException {
          List<String> entityClassifications = getClassificationNames(guid);
  
          for (AtlasClassification classification : classifications) {
              String newClassification = classification.getTypeName();
  
              if (CollectionUtils.isNotEmpty(entityClassifications) && entityClassifications.contains(newClassification)) {
                  throw new AtlasBaseException(AtlasErrorCode.INVALID_PARAMETERS, "entity: " + guid +
                          ", already associated with classification: " + newClassification);
              }
          }
      }
docs: Validate if classification is not already associated with the entities
  
  @param guid            unique entity id
  @param classifications list of classifications to be associated