Repository Key Function SPI

[cstamas]

New opt-in experimental feature for enhanced local repository: ability to choose "repository key" function. Local repository (simple and enhanced) by default uses the simple key (historically) where other places all used nid. Have to note, that simple is technically equivalent to nid as RemoteRepository.isRepositoryManager() is not set anywhere in Maven.

Added key functions:

• simple -> the original code in LRM
• nid -> norm(id) (path friendly)
• hurl -> sha1(url)
• nid_hurl -> norm(id)-sha1(url)
• gurk -> norm(id)-sha1(seed) where "seed" is all config properties of repo
• ngurk -> norm(id)-sha1(seed) where "seed" is all config sans mirror list (just the string "isMirrored" is added for mirrors)

Introduced RepositoryKeyFunction type, that is used consistently in enhanced local repository (availability calculation), prefix composer (split repository prefix calculation) and remote repository manager (remote repository consolidation). This is new SPI, and impl provides default implementation with those above.

[gnodet]

New opt-in experimental feature for enhanced local repository: ability to choose "repository key" function. Local repository (simple and enhanced) by default uses the simple key (historically) where other places all used nid. Have to note, that simple is technically equivalent to nid as RemoteRepository.isRepositoryManager() is not set anywhere in Maven.

Added key functions:

• simple -> the original code in LRM
• nid -> norm(id) (path friendly)
• hurl -> sha1(url)
• nid_hurl -> norm(id)-sha1(url)
• gurk -> norm(id)-sha(seed) where "seed" is all config properties of repo
• ngurk -> norm(id)-sha(seed) where "seed" is all config sans mirror list (just the string "isMirrored" is added for mirrors)

Fwiw, since this is switching to a more mathematical expression, I was confused by the - which, when I first read, though it was minus. I wonder if we could use a different separator such as + or ..