NEXUS-5472: WIP
NEXUS-5472: Added missing license headers to make CI build this
NEXUS-5472: modifier methods renamed to more appropriate ones.

And other smaller fixes.
NEXUS-5472: Javadoc
NEXUS-5472: Added UT for WritableEntrySourceModifierImplTest

While doing UT, simplified WL matcher a lot, and also modified
and simplified the modifier itself too (was trying to be too smart)
NEXUS-5472: Renamed things to better match their purpose
NEXUS-5472: License was missing
NEXUS-5472: Smaller fixes and comments
NEXUS-5472: Javadoc and comments
Merge remote-tracking branch 'origin/master' into nexus-5472-proxy404
NEXUS-5472: Multiple fixes combo

Those are:
* Added LocalWalkerStrategy UT
* fixed LocalWalkerStrategy, as nexus may leave empty folders on artifact removal (it does not enforce remote folder removal when delete over REST or UI the given file, but tasks like snap remover DOES delete empty parents) and it was gathering folders too, hence, creating "false" WL entries even if folder was empty, artifact not present, it was added to WL. Now, _files_ are scanned (downsize, walking will be slower!), but real content is added now to WL.
* aligned hosted repo WL creation (walk) and maintenance (offer/revoke), as the two was falling apart (deploying created full path lists while init or delete+update of WL created capped depth list). Now both behave same, as this is fine as only hosted repo WLs are maintained by Nexus
* separated local and remote scrape depths for real
NEXUS-5472: Javadoc on merging ES
NEXUS-5472: Shortcut WL update propagation

It was dumb to listen to our own events to propagate WL updates.
Shortcutting it, as WLManager handles that now (in private).
Merge remote-tracking branch 'origin/master' into nexus-5472-proxy404
NEXUS-5472: Smaller fixes and javadoc.

Getting rid of warnings.
Also, merging ES fixed to merge once and provide same result
over and over again, to lessen the possibility of having a "window"
where group members reported as having WL and actual publishing the
group WL
NEXUS-5472: Strategy refactor

Lessen code duplication.

Also, lessen warnings, added javadoc.
NEXUS-5472: More tests for reading pref file
NEXUS-5472: More UTs and fixes

Those are:
* added UTs for two more classes
* changed how EventDispatcher is started
* flipped default value to the intended one (UT fixes in master incoming)
* some minor fixes
Merge remote-tracking branch 'origin/master' into nexus-5472-proxy404
Merge remote-tracking branch 'origin/master' into nexus-5472-proxy404