Potential NPE in RunnableOnMaster

[kwin]

The class RunnableOnMaster implements a TopologyEventListener and dereferences TopologyEvent.getNewView() in its handleTopologyEvent method (

acs-aem-commons/bundle/src/main/java/com/adobe/acs/commons/util/RunnableOnMaster.java

Line 45 in 05e6e86

this.isLeader = te.getNewView().getLocalInstance().isLeader();

).

This might lead to a NPE as getNewView might return null (https://helpx.adobe.com/experience-manager/6-5/sites/developing/using/reference-materials/javadoc/org/apache/sling/discovery/TopologyEvent.html#getNewView--). In general it is not wise to rely on the TopologyEventListener just to figure out if the current instance is the leader, as you cannot predict when the topology events are received. Instead one should rely on DiscoveryService.getTopologyView() as that always gives the current status.

A similar issue was detected in #2492