HADOOP-19826. Add contract test to verify renaming empty dir works

[steveloughran]

How was this patch tested?

Test for handling of empty dirs; surprised we didn't have this in already.

For code changes:

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[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 36s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell was not available.
+0 🆗	detsecrets	0m 0s		detect-secrets was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
+1 💚	test4tests	0m 0s		The patch appears to include 1 new or modified test files.
			_ trunk Compile Tests _
+1 💚	mvninstall	43m 25s		trunk passed
+1 💚	compile	16m 10s		trunk passed with JDK Ubuntu-21.0.10+7-Ubuntu-124.04
+1 💚	compile	16m 40s		trunk passed with JDK Ubuntu-17.0.18+8-Ubuntu-124.04.1
+1 💚	checkstyle	1m 13s		trunk passed
+1 💚	mvnsite	1m 47s		trunk passed
+1 💚	javadoc	1m 28s		trunk passed with JDK Ubuntu-21.0.10+7-Ubuntu-124.04
+1 💚	javadoc	1m 23s		trunk passed with JDK Ubuntu-17.0.18+8-Ubuntu-124.04.1
+1 💚	spotbugs	3m 11s		trunk passed
+1 💚	shadedclient	30m 10s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	1m 12s		the patch passed
+1 💚	compile	15m 13s		the patch passed with JDK Ubuntu-21.0.10+7-Ubuntu-124.04
+1 💚	javac	15m 13s		the patch passed
+1 💚	compile	16m 29s		the patch passed with JDK Ubuntu-17.0.18+8-Ubuntu-124.04.1
+1 💚	javac	16m 29s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	1m 27s		the patch passed
+1 💚	mvnsite	1m 58s		the patch passed
+1 💚	javadoc	1m 25s		the patch passed with JDK Ubuntu-21.0.10+7-Ubuntu-124.04
+1 💚	javadoc	1m 22s		the patch passed with JDK Ubuntu-17.0.18+8-Ubuntu-124.04.1
+1 💚	spotbugs	3m 14s		the patch passed
+1 💚	shadedclient	30m 3s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	22m 5s		hadoop-common in the patch passed.
+1 💚	asflicense	1m 11s		The patch does not generate ASF License warnings.
		213m 18s

Subsystem	Report/Notes
Docker	ClientAPI=1.53 ServerAPI=1.53 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8283/1/artifact/out/Dockerfile
GITHUB PR	#8283
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
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Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8283/1/testReport/
Max. process+thread count	1403 (vs. ulimit of 5500)
modules	C: hadoop-common-project/hadoop-common U: hadoop-common-project/hadoop-common
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8283/1/console
versions	git=2.43.0 maven=3.9.11 spotbugs=4.9.7
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[steveloughran]

Ran the tests through s3a, abfs and gs connectors

[steveloughran]

missed this was approved, and as #8304 is a better test, gone with that one