CopyOnReadStatsMBean Service Missing during AEM 6.5 Upgrade

[RishabhSinha]

While upgrading to 6.5.12, I observed that service "org.apache.jackrabbit.oak.plugins.index.lucene.CopyOnReadStatsMBean" is missing from oak-lucene.jar (1.22.9) and is not registered, because of which the indexCopier is not present and hence NPE is thrown during an OTB job.

Any idea what could cause this CopyOnReadStatsMBean missing? 

I do not see anything in logs related to this. The bundle refresh or update is not resolving this as well.

[kautuk_sahni]

@Mahedi_Sabuj @A_H_M_Imrul @ShaileshBassi @Sady_Rifat @aanchal-sikka Can you please review this unanswered question? Appreciate your thoughts on this.