fix: fix some additional minor bugs in muc search
1. typo nameIsExactMatch should be name_is_exact_match
2. check subject for null value AND empty string
OF-2239: Introduce new cache to be used by plugins
When plugins use the standard caches (in a cluster), ClassCastExceptions will occur after a plugin that has seen usage is reloaded/updated.
To prevent these exceptions, a new cache is introduced by this commit that stores data without a reference to the classes that define the data.
Emiel van der Herberg <emiel.van.der.herberg@marviq.com>
7f678690303971c32690f33b6e922621a140dc71
OF-2165 First setup of nickname collision handling. Work in progress.
