Merge branch 'master' into stable-6.5

* master:
  Externalize strings introduced in c9552aba
  Silence API error introduced by 596c445a
  PackConfig: add entry for minimum size to index
  Fix getPackedRefs to not throw NoSuchFileException
  PackObjectSizeIndex: interface and impl for the object-size index
  UInt24Array: Array of unsigned ints encoded in 3 bytes.
  PackIndex: expose the position of an object-id in the index
  Add pack options to preserve and prune old pack files
  DfsPackFile/DfsGC: Write commit graphs and expose in pack
  ObjectReader: Allow getCommitGraph to throw IOException
  Allow to perform PackedBatchRefUpdate without locking loose refs
  Document option "core.sha1Implementation" introduced in 59029aec
  UploadPack: consume delimiter in object-info command
  PatchApplier fix - init cache with provided tree
  Avoid error-prone warning
  Fix unused exception error-prone warning
  UploadPack: advertise object-info command if enabled
  Move MemRefDatabase creation in a separate method.
  DfsReaderIoStats: Add Commit Graph fields into DfsReaderIoStats

Change-Id: Ic9f91f2139432999b99c444302457b3c08911009