When model has multiple DRDs and tries to reuse a decision component by adding it into a Decision Service node, the resulting Decision Service node has no inputData definitions.

In multiple DRDs models the ultimate decision components representation should reflect all the relations merged from their occurrences - i.e. in this case it should not matter that the Input is not defined directly in the DRD with the Decision Service. The Decision Service should inherit the inputData elements based on what inputs do the included decisions have.

See call centre drd.dmn .

That's a multiple DRD model with Decision Service office accepts the call which suffers from this issue, in the file the fix is already applied - by adding the

<dmn:inputData href="#_4208DF15-2342-46EA-8EFF-E402FDDC2F5E"/> 

so that the resulting decisionService definition is

  <dmn:decisionService id="_D36C61E4-C5DB-4375-855B-D58A0269A570" name="office accepts the call">
    <dmn:extensionElements/>
    <dmn:variable id="_EDEE0B3D-2B82-4FDE-B725-4ECFBE8F8768" name="office accepts the call" typeRef="boolean"/>
    <dmn:outputDecision href="#_25C72B4D-63EF-406F-89C6-612B2090E984"/>
    <dmn:encapsulatedDecision href="#_4F791054-DEBD-4EA7-95BA-9E4695239822"/>
    <dmn:encapsulatedDecision href="#_606C3BEC-097B-4DA4-9209-9BBA72EBCEF1"/>
    <dmn:inputData href="#_4208DF15-2342-46EA-8EFF-E402FDDC2F5E"/>
  </dmn:decisionService>

When the decision endpoint is invoked (before applying the workaround) the evaluation fails and log contains following:

ERROR [org.kie.dmn.core.ast.DMNDecisionServiceFunctionDefinitionEvaluator] (default task-35) Parameter count mismatch invoking decision service function 'office accepts the call'