[APIM 4.1.0] NPE in AnalyticsMetricsHandler When Axis2Sender.sendBack() Is Called Inside Custom Mediator in Request Flow with Analytics Enabled

[JanithaSampathBandara]

Description

Following error is encountered when invoking APIs whereas a custom class mediator attached as a policy when analytics enabled.

ERROR - AnalyticsMetricsHandler Error Occurred when collecting data
java.lang.NullPointerException: null
	at org.wso2.carbon.apimgt.gateway.handlers.analytics.SynapseAnalyticsDataProvider.getBackendLatency_aroundBody54(SynapseAnalyticsDataProvider.java:404) ~[org.wso2.carbon.apimgt.gateway_9.20.74.295.jar:?]
	at org.wso2.carbon.apimgt.gateway.handlers.analytics.SynapseAnalyticsDataProvider.getBackendLatency(SynapseAnalyticsDataProvider.java:399) ~[org.wso2.carbon.apimgt.gateway_9.20.74.295.jar:?]
	at org.wso2.carbon.apimgt.gateway.handlers.analytics.SynapseAnalyticsDataProvider.getLatencies_aroundBody18(SynapseAnalyticsDataProvider.java:217) ~[org.wso2.carbon.apimgt.gateway_9.20.74.295.jar:?]
	at org.wso2.carbon.apimgt.gateway.handlers.analytics.SynapseAnalyticsDataProvider.getLatencies(SynapseAnalyticsDataProvider.java:215) ~[org.wso2.carbon.apimgt.gateway_9.20.74.295.jar:?]
	at org.wso2.carbon.apimgt.common.analytics.collectors.impl.SuccessRequestDataCollector.collectData(SuccessRequestDataCollector.java:71) ~[org.wso2.carbon.apimgt.common.analytics_9.20.74.289.jar:?]
	at org.wso2.carbon.apimgt.common.analytics.collectors.impl.GenericRequestDataCollector.collectData(GenericRequestDataCollector.java:46) ~[org.wso2.carbon.apimgt.common.analytics_9.20.74.289.jar:?]
	at org.wso2.carbon.apimgt.gateway.handlers.analytics.AnalyticsMetricsHandler.handleResponseOutFlow_aroundBody8(AnalyticsMetricsHandler.java:95) ~[org.wso2.carbon.apimgt.gateway_9.20.74.295.jar:?]
	at org.wso2.carbon.apimgt.gateway.handlers.analytics.AnalyticsMetricsHandler.handleResponseOutFlow(AnalyticsMetricsHandler.java:81) ~[org.wso2.carbon.apimgt.gateway_9.20.74.295.jar:?]
	at org.apache.synapse.core.axis2.Axis2Sender.sendBack(Axis2Sender.java:188) ~[synapse-core_2.1.7.wso2v271_66.jar:2.1.7-wso2v271.66]
	at org.example.AuthFailure.mediate(AuthFailure.java:53) ~[AuthFailure-1.0-SNAPSHOT.jar:?]
	at org.apache.synapse.mediators.ext.ClassMediator.updateInstancePropertiesAndMediate(ClassMediator.java:182) ~[synapse-core_2.1.7.wso2v271_66.jar:2.1.7-wso2v271.66]
...

Steps to Reproduce

1. Get an APIM 4.1.0 U2-177 pack and enable analytics [1].
2. Implement and add the class mediator to the /lib folder.
3. Create a sample API and add the implementation as a custom policy in the request flow of a resource.
4. Invoke the API and the pointed error trace can be observed in the wso2carbon.log file.

Note : Noticed the same behaviour when adding a mediator as a custom policy.

[1] https://apim.docs.wso2.com/en/4.1.0/api-analytics/on-prem/elk-installation-guide/#step-1-configuring-api-manager

Version

4.1.0

Environment Details (with versions)

No response