Merge branch 'stable-5.10'
* stable-5.10:
Remove unused imports
Silence API warnings
Remove erraneously merged source features
Prepare 5.3.9-SNAPSHOT builds
JGit v5.3.8.202011260953-r
Prepare 5.1.15-SNAPSHOT builds
JGit v5.1.14.202011251942-r
GC#deleteOrphans: log warning for deleted orphaned files
GC#deleteOrphans: handle failure to list files in pack directory
Ensure that GC#deleteOrphans respects pack lock
PacketLineIn: ensure that END != DELIM
Update API warning filters
Remove unused imports
Change-Id: I25f50c3807a4e6b22a264320ea7ed3758e2a75ec
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>