Test Scenario: wrong management of null values with simple types in DMN scenarios

See reproducer dmn-sandbox-master.zip

Test Scenario

DMN

11:45:04,120 ERROR [org.kie.dmn.core.ast.DMNDTExpressionEvaluator] (default task-60) Contract Type='{}' does not match any of the valid values null for decision table 'Contract Identification'.