* [releng] japicmp: update last release version

* Merge branch 'stable-5.10'

* Merge branch 'stable-5.9' into stable-5.10

* Merge branch 'stable-5.8' into stable-5.9

* Merge branch 'stable-5.7' into stable-5.8

* Merge branch 'stable-5.6' into stable-5.7

* Merge branch 'stable-5.5' into stable-5.6

* Merge branch 'stable-5.4' into stable-5.5

* Remove unused imports
* Silence API warnings
* Remove erraneously merged source features

* Merge branch 'stable-5.6' into stable-5.7

* Merge branch 'stable-5.5' into stable-5.6

* Merge branch 'stable-5.4' into stable-5.5

* Merge branch 'stable-5.3' into stable-5.4

* Prepare 5.3.9-SNAPSHOT builds

* Add support for reading symrefs from pack capabilities

* JGit v5.3.8.202011260953-r

* Merge branch 'stable-5.2' into stable-5.3

* Merge branch 'stable-5.1' into stable-5.2

* 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

* Merge branch 'stable-5.10'

* Prepare 5.10.0-SNAPSHOT builds

* JGit v5.10.0.202011251205-m3
* Merge branch 'master' into stable-5.10

* PacketLineIn: ensure that END != DELIM

* Update Orbit to S20201118210000 and add target for 4.18

* Merge branch 'stable-5.9'

* PacketLineIn: ensure that END != DELIM

* PacketLineIn: ensure that END != DELIM

* Allow to resolve a conflict by checking out a file

* Update Orbit to I20201111205634

* Document that setLastModified sets time of symlink target

* Fix bug in PerformanceLogContext

* Fix IOException occurring during gc

* Prepare 5.10.0-SNAPSHOT builds

* JGit v5.10.0.202011041322-m2

* Revert "Client-side protocol V2 support for fetching"

* Close Repository to fix tests failing on Windows

* Client-side protocol V2 support for fetching

* Update slf4j to 1.7.30
* Update Orbit to S20201027182932 (2020-12 M2)

* Fix formatting of config option values

* Document options in core section supported by JGit

* Ensure .gitmodules is loaded when accessing submodule name

* Export new package org.eclipse.jgit.logging and import it where used

* Ensure GC.deleteOrphans() can delete read-only orphaned files on Windows

* Add new performance logging

* Compute time differences with Duration

* Implement git describe --all

* Override config http.userAgent from environment GIT_HTTP_USER_AGENT

* Upgrade spotbugs-maven-plugin to 4.1.3

* Fix OperatorPrecedence warning flagged by error prone