HADOOP-19502. Add RegexpSingleline module to checkstyle.xml.

[hfutatzhanghb]

Description of PR

JIRA: HADOOP-19502. Add RegexpSingleline module to checkstyle.xml.

Add RegexpSingleline module to checkstyle.xml.
In my local, checkstyle tools use checkstyle.xml can not detect blanks.

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 31s		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.
+0 🆗	xmllint	0m 0s		xmllint was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
-1 ❌	test4tests	0m 0s		The patch doesn't appear to include any new or modified tests. Please justify why no new tests are needed for this patch. Also please list what manual steps were performed to verify this patch.
			_ trunk Compile Tests _
+1 💚	mvninstall	36m 5s		trunk passed
+1 💚	compile	0m 24s		trunk passed with JDK Ubuntu-11.0.26+4-post-Ubuntu-1ubuntu120.04
+1 💚	compile	0m 24s		trunk passed with JDK Private Build-1.8.0_442-8u442-b06us1-0ubuntu120.04-b06
+1 💚	mvnsite	0m 24s		trunk passed
+1 💚	javadoc	0m 33s		trunk passed with JDK Ubuntu-11.0.26+4-post-Ubuntu-1ubuntu120.04
+1 💚	javadoc	0m 24s		trunk passed with JDK Private Build-1.8.0_442-8u442-b06us1-0ubuntu120.04-b06
+1 💚	shadedclient	71m 24s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 16s		the patch passed
+1 💚	compile	0m 14s		the patch passed with JDK Ubuntu-11.0.26+4-post-Ubuntu-1ubuntu120.04
+1 💚	javac	0m 14s		the patch passed
+1 💚	compile	0m 14s		the patch passed with JDK Private Build-1.8.0_442-8u442-b06us1-0ubuntu120.04-b06
+1 💚	javac	0m 14s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	mvnsite	0m 14s		the patch passed
+1 💚	javadoc	0m 14s		the patch passed with JDK Ubuntu-11.0.26+4-post-Ubuntu-1ubuntu120.04
+1 💚	javadoc	0m 15s		the patch passed with JDK Private Build-1.8.0_442-8u442-b06us1-0ubuntu120.04-b06
+1 💚	shadedclient	34m 26s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	0m 19s		hadoop-build-tools in the patch passed.
+1 💚	asflicense	0m 38s		The patch does not generate ASF License warnings.
		109m 44s

Subsystem	Report/Notes
Docker	ClientAPI=1.48 ServerAPI=1.48 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7505/1/artifact/out/Dockerfile
GITHUB PR	#7505
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient codespell detsecrets xmllint
uname	Linux 243e431c62db 5.15.0-134-generic #145-Ubuntu SMP Wed Feb 12 20:08:39 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 91ab935
Default Java	Private Build-1.8.0_442-8u442-b06us1-0ubuntu120.04-b06
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.26+4-post-Ubuntu-1ubuntu120.04 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_442-8u442-b06us1-0ubuntu120.04-b06
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7505/1/testReport/
Max. process+thread count	623 (vs. ulimit of 5500)
modules	C: hadoop-build-tools U: hadoop-build-tools
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7505/1/console
versions	git=2.25.1 maven=3.6.3
Powered by	Apache Yetus 0.14.0 https://yetus.apache.org

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[hfutatzhanghb]

Hi, @slfan1989 . Could you please help review this PR when have free time? Thanks ahead!

[slfan1989]

@hfutatzhanghb Thanks for the contribution! LGTM.

[slfan1989]

@steveloughran Could you please review this pr? Thank you very much!

[slfan1989]

@hfutatzhanghb If there are no other comments, I will merge this pr tomorrow.

[hfutatzhanghb]

@hfutatzhanghb If there are no other comments, I will merge this pr tomorrow.

@slfan1989 Thanks a lot!!!

[slfan1989]

@hfutatzhanghb Thanks for the contribution!