How to implement with JGit 'git show <commit>'?

I am looking for a way to receive with JGit the same result as is provided by the 'git show' command. The technique with using git-diff as shown in jgit cookbook does not work correctly for merge commits. Particularly, 'git show' on merge commit does not show files, which were just merged, while JGit diff implementation shows the merged files as changed.