Merge stable-2.13 into master

* stable-2.13:
  Rename isValidPath to isAllowedPath
  Use Path instead of File
  Rename configFile to resolveFile
  Fix Eclipse warning: properly close DiffFormatter
  Use try-with-resources instead of the old-style finally block

Change-Id: I1f0180a428988126d1ddc99fd5d29436f8370c52