philipdnichols opened a new issue, #6448:
URL: https://github.com/apache/incubator-kie-drools/issues/6448
## Issue Details
**Affected Version:** 10.1.0
**Component:** kie-dmn-core
## Description
When implementing a custom DMN runtime event listener (extending
`DefaultDMNRuntimeEventListener`) to log decision service execution, the
utility method `DMNEventUtils.extractDSOutputDecisionsValues()` throws a
NullPointerException when processing decision services from models that include
other models with different namespaces.
## Use Case
We use a custom logging listener to capture decision service inputs/outputs
for audit and debugging purposes:
```java
public class DecisionLoggingListener extends DefaultDMNRuntimeEventListener {
@Override
public void
afterEvaluateDecisionService(AfterEvaluateDecisionServiceEvent event) {
var outputs = DMNEventUtils.extractDSOutputDecisionsValues(event);
logger.debug("Decision Service outputs: " + outputs);
// ... additional logging logic
}
}
```
## Root Cause
The method at line 70 of `org.kie.dmn.core.impl.DMNEventUtils` calls
`getDecisionById(id).getName()` without checking if `getDecisionById(id)`
returns null. When decision IDs contain namespace information from included
models, `getDecisionById()` returns null because it cannot find decisions with
namespace-prefixed IDs, causing the NPE.
## Stack Trace
```
java.lang.NullPointerException: Cannot invoke
"org.kie.dmn.api.core.ast.DecisionNode.getName()" because the return value of
"org.kie.dmn.api.core.DMNModel.getDecisionById(String)" is null
at
org.kie.dmn.core.impl.DMNEventUtils.extractDSOutputDecisionsValues(DMNEventUtils.java:70)
at
com.example.DecisionLoggingListener.afterEvaluateDecisionService(DecisionLoggingListener.java:xx)
at
org.kie.dmn.core.impl.DMNRuntimeEventManagerUtils.fireAfterEvaluateDecisionService(DMNRuntimeEventManagerUtils.java:81)
at
org.kie.dmn.core.ast.DMNDecisionServiceEvaluator.evaluate(DMNDecisionServiceEvaluator.java:111)
```
## Steps to Reproduce
1. Create a parent DMN model that includes a child model from a different
namespace
2. Have the child model contain a decision service with output decisions
3. Register a custom DMN runtime listener that calls
`DMNEventUtils.extractDSOutputDecisionsValues()` in
`afterEvaluateDecisionService()`
4. Evaluate the decision service
5. The listener's event processing will fail with NPE
## Expected Behavior
The `DMNEventUtils.extractDSOutputDecisionsValues()` utility method should
safely handle namespace-prefixed decision IDs and extract output values
correctly for use in logging listeners.
## Actual Behavior
NPE is thrown when attempting to call getName() on a null DecisionNode,
breaking the logging functionality.
## Impact
This prevents proper logging/auditing of decision service executions when
using included models, which is a common pattern in complex DMN implementations.
## Workaround
Implement a custom extraction method in the logging listener that handles
null returns from getDecisionById() with fallback strategies instead of using
the utility method.
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