For readability. The current implementation is a sequence of
7 (!) array_…() function calls. It is also not free from bugs.
If one of the two inputs (ExtensionRegistry and Config) specifies
namespaces by e.g. canonical name, but the other by number,
the two are not properly merged. It should be possible to use
configuration to disable a namespace that would otherwise be
enabled. This currently works only if both use the same array
keys.
Bug: T291727
Change-Id: I2671f391cdc510da21eda8a1dc5ed4d2513a378a