Major Description
looking at the query code base in the light of OAK-6069 i came across o.a.j.oak.query.QueryEngineSettingsMBeanImpl wondering why we have 2 implementations of the QueryEngineSettingsMBean interface in the same package. While QueryEngineSettings is widely used across the oak code base the QueryEngineSettingsMBeanImpl has a single usage in the o.a.j.oak.Oak helper class.
tmueller explained me the reason for having this additional implementation (instead of having just a single one). however, i would suggest to make QueryEngineSettingsMBeanImpl an inner class of the Oak helper and thus ensure that it's not used mistakenly or causes extra confusion (as it did for me 
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