[boost] [boostbook] Doxygen nested namespaces entities not being handled

I am seeing an issue where nested namespace doxygen documented entities are not being generated by BoostBook for the final documentation of a reference section in a library's documentation. I am using the quickbook -> boostbook -> html set of tools in the doc jamfile. If I just use doxygen directly to generate the documentation the nested namespace entities are there, so this appears to be a BoostBook problem. Has this problem always existed ? Has anyone else ever encountered it ? I first reported this as a Boost Build issue at https://github.com/bfgroup/b2/issues/18, but then reported this at https://github.com/boostorg/boostbook/issues/10.