question: public final void incRef ( ) { ensureOpen ( ) ; refCount . incrementAndGet ( ) ; }
target:  Expert: increments the refCount of this TaxonomyReader instance. RefCounts can be used to determine when a taxonomy reader can be closed safely, i.e. as soon as there are no more references. Be sure to always call a corresponding decRef(), in a finally clause; otherwise the reader may never be closed.