What follows is three example commits. In all cases 'git show' explains correctly, yet for merge commits the two API's give inconsistent results.
Consider this merge commit #1, 'git show' *correctly shows the changes to the files* (file A was developer resolved, file B was auto-merged, file C was included w/out file-level merge changes (no new revision)):
$ git show c47af8deac6b87a
commit c47af8deac6b87a35c54f750166a13089c35b770 (HEAD -> master, origin/PR2, PR2)
Merge: 4a7b7ed 705cb5f
Author: Joe
Date: Fri Mar 18 14:27:03 2022 -0400
Merge branch 'master' into PR2
diff --cc A
index bb62e45,c875e2d..695279f
--- a/A
+++ b/A
adios
more stuff
+take that!
+ hello
+ what are we doing
+ this is it
+ more of the same
+ gimme a break
diff --cc B
index fecdf68,864a49b..aa01e7f
--- a/B
+++ b/B
-guten tag
this is getting ridiculous
- what now?
- ho hum
goodbye
more changes
uh-oh
However the Java API shows three changes (when iterating through the changesets for that commit):
2022-03-18 19:46:16,817 WARN [c.o.s.r.ScriptBindingsManager]: Type: MODIFY
2022-03-18 19:46:16,817 WARN [c.o.s.r.ScriptBindingsManager]: Path: A
2022-03-18 19:46:16,817 WARN [c.o.s.r.ScriptBindingsManager]: Type: MODIFY
2022-03-18 19:46:16,818 WARN [c.o.s.r.ScriptBindingsManager]: Path: B
2022-03-18 19:46:16,818 WARN [c.o.s.r.ScriptBindingsManager]: Type: MODIFY
2022-03-18 19:46:16,818 WARN [c.o.s.r.ScriptBindingsManager]: Path: C
While the REST API shows no changes (.../commits/c47af8d/changes):
{"fromHash":null,"toHash":"c47af8d","properties":{},"values":[],"size":0,"isLastPage":true,"start":0,"limit":25,"nextPageStart":null}
Consider this merge commit #2, 'git show' *correctly shows that there are no changes to any files* (files A and C were included, but no new file revisions via file-level merge):
$ git show 8907e98fb71ffca612
commit 8907e98fb71ffca6120f703d0e43be4787dd173e
Merge: edb85da 2d76267
Author: Joe
Date: Thu Mar 17 12:57:40 2022 -0400
Merge branch 'master' into PR2
However the Java API shows two changes:
2022-03-18 19:53:38,354 WARN [c.o.s.r.ScriptBindingsManager]: Type: MODIFY
2022-03-18 19:53:38,373 WARN [c.o.s.r.ScriptBindingsManager]: Path: A
2022-03-18 19:53:38,374 WARN [c.o.s.r.ScriptBindingsManager]: Type: MODIFY
2022-03-18 19:53:38,374 WARN [c.o.s.r.ScriptBindingsManager]: Path: C
While the REST API shows no changes (.../commits/8907e98/changes):
{"fromHash":null,"toHash":"8907e98","properties":{},"values":[],"size":0,"isLastPage":true,"start":0,"limit":25,"nextPageStart":null}
For a simple (non-merge) commit, results are as expected (file A is modified):
$ git show 4a7b7ed55
commit 4a7b7ed55512a5814292ba6b1689a781c4dc225b
Author: Joe
Date: Fri Mar 18 14:24:44 2022 -0400
PR2
diff --git a/A b/A
index 76b9b5a..bb62e45 100644
--- a/A
+++ b/A
adios
more stuff
+take that!
2022-03-18 20:11:46,977 WARN [c.o.s.r.ScriptBindingsManager]: Type: MODIFY
2022-03-18 20:11:47,012 WARN [c.o.s.r.ScriptBindingsManager]: Path: A
{"fromHash":null,"toHash":"4a7b7ed55","properties":{},"values":[{"contentId":"bb62e451e87164abcba481ef8f73d719230e0b62","fromContentId":"76b9b5ab7d2242c33ab6ee0d9ede24233add0b66","path":{"components":["A"],"parent":"","name":"A","toString":"A"},"executable":false,"percentUnchanged":-1,"type":"MODIFY","nodeType":"FILE","srcExecutable":false,"links":{...},"properties":{"gitChangeType":"MODIFY"}}],"size":1,"isLastPage":true,"start":0,"limit":25,"nextPageStart":null}
