While testing my code for NIFI-10612 <https://issues.apache.org/jira/browse/NIFI-10612>, in order to get an attribute which was empty, I tried using the UpdateAttribute processor with basic usage to add a dynamic property without any value. I was not able to do so. I realized the code does not allow for it as there is a non-empty validator on dynamic property descriptors which are not stateful in UpdateAttribute <https://github.com/apache/nifi/blob/753cb1b9df781232d953c6602200aca332f4d019/nifi-nar-bundles/nifi-update-attribute-bundle/nifi-update-attribute-processor/src/main/java/org/apache/nifi/processors/attributes/UpdateAttribute.java#L248>. The only way I could get an empty attribute was by using value
${literal('')} > (a trick a friend told me and which I found on this <https://stackoverflow.com/questions/57438603/how-to-set-an-attribute-to-be-a-blank-string-in-nifi> Stackoverflow post). Why can't the property be blank and thereby have the attribute created on the flow file be empty?