code: private String createIdentifier(JsonNode object) {
  		JsonNode idNode = object.get(ID);
  
  		String id = idNode != null ? idNode.asText().trim() : "";
  
  		if (id.isEmpty() && deserializationFeatures.contains(DeserializationFeature.REQUIRE_RESOURCE_ID)) {
  			throw new IllegalArgumentException(String.format("Resource must have a non null and non-empty 'id' attribute! %s", object.toString()));
  		}
  
  		String type = object.get(TYPE).asText();
  		return type.concat(id);
  	}
docs: Generates unique resource identifier by combining resource type and resource id fields. <br />
  By specification id/type combination guarantees uniqueness.
  @param object data object
  @return concatenated id and type values