Merge branch 'stable-5.1'

Merge branch 'stable-5.1'

* stable-5.1:
  Prepare 5.1.4-SNAPSHOT builds
  JGit v5.1.3.201810200350-r
  Prepare 4.11.6-SNAPSHOT builds
  JGit v4.11.5.201810191925-r
  Prepare 4.9.8-SNAPSHOT builds
  JGit v4.9.7.201810191756-r
  Update API problem filter
  Prepare 4.7.7-SNAPSHOT builds
  JGit v4.7.6.201810191618-r
  Update API problem filter
  Fix file handle leak in ObjectDownloadListener.onWritePossible
  Replace Findbugs with Spotbugs in org.eclipse.jgit/pom.xml
  Replace FindBugs with SpotBugs
  Prepare 4.4.2-SNAPSHOT builds
  JGit v4.0.3.201509231615-r

Change-Id: Ic8b2189fdd8403294327a17cc0c1f6a6e2f78cb8
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>