How to use null safe operator in drools decision table -

please let me know how use ".?" (null safe operator) in drools decision table(spreadsheet). attached spreadsheet, mdcl object need add null safe operator. please let me know if need add additional information, i'm new drools.

the null-safe operator in drools !., not .? - see documentation. can use inside decision tables when writing rules.

in example, change condition mdcl.mdcl_health.get("mdcl").value mdcl!.mdcl_health.get("mdcl").value fire rule if mdcl not null.