[ https://issues.redhat.com/browse/DROOLS-5438?page=com.atlassian.jira.plug... ] Matteo Mortari commented on DROOLS-5438: ---------------------------------------- [~swiderski.maciej] difficult to understand without the full context, but the message you reported in snippet is different, it doesn't look like ``` sum([]) = null ``` which is ensured by this test: https://github.com/kiegroup/drools/blame/master/kie-dmn/FEELbuiltinfuncti... but it seems you are calling with ``` sum(null) ``` which is something different. Please be aware there is a pending issue being resolved as part of the `nn sum()` which might be at play somehow, there too. I remember something with null parameter by Simon, but to be checked. Can you check it is a different use case indeed? -- This message was sent by Atlassian Jira (v7.13.8#713008)