checkstyle: FTBFS: ant-phase-compile.xml:14: java.lang.NullPointerException

Imported from Debian bug http://bugs.debian.org/735786:

Source: checkstyle
Version: 5.6-2
Severity: serious
Tags: jessie sid
User: <email address hidden>
Usertags: qa-ftbfs-20140114 qa-ftbfs
Justification: FTBFS on amd64

Hi,

During a rebuild of all packages in sid, your package failed to build on
amd64.

Relevant part (hopefully):
> debian/rules build
> test -x debian/rules
> mkdir -p "."
> /usr/share/maven-debian-helper/copy-repo.sh /«PKGBUILDDIR»/debian
> mh_patchpoms -pcheckstyle --debian-build --keep-pom-version --maven-repo=/«PKGBUILDDIR»/debian/maven-repo
> touch debian/stamp-poms-patched
> # before-build target may be used to unpatch the pom files, so we need to check if
> # patching the pom files is needed here, normally not
> if [ ! -f pom.xml.save ]; then \
> /usr/bin/make -f debian/rules patch-poms; \
> fi
> cd . && /usr/lib/jvm/default-java/bin/java -noverify -cp /usr/share/maven2/boot/classworlds.jar:/usr/lib/jvm/default-java/lib/tools.jar -Dclassworlds.conf=/etc/maven2/m2-debian.conf org.codehaus.classworlds.Launcher -s/etc/maven2/settings-debian.xml -Dmaven.repo.local=/«PKGBUILDDIR»/debian/maven-repo package
> [INFO]
> NOTE: Maven is executing in offline mode. Any artifacts not already in your local
> repository will be inaccessible.
>
> [INFO] Scanning for projects...
> [INFO] ------------------------------------------------------------------------
> [INFO] Building checkstyle
> [INFO] task-segment: [package]
> [INFO] ------------------------------------------------------------------------
> [INFO] [enforcer:enforce {execution: enforce-versions}]
> [INFO] [antlr:generate {execution: default}]
> [INFO] performing grammar generation [java.g]
> ANTLR Parser Generator Version 2.7.7 (20130425) 1989-2005
> /«PKGBUILDDIR»/src/checkstyle/com/puppycrawl/tools/checkstyle/grammars/java.g:919: warning:Syntactic predicate superfluous for single alternative
>
> [INFO] [resources:resources {execution: default-resources}]
> [INFO] Using 'iso-8859-1' encoding to copy filtered resources.
> [INFO] Copying 130 resources
> [INFO] Copying 1 resource
> [WARNING] POM for 'org.codehaus.plexus:plexus-compiler-api:pom:debian:runtime' is invalid.
>
> Its dependencies (if any) will NOT be available to the current build.
> [WARNING] POM for 'org.codehaus.plexus:plexus-compiler-javac:pom:debian:runtime' is invalid.
>
> Its dependencies (if any) will NOT be available to the current build.
> [INFO] [compiler:compile {execution: default-compile}]
> [INFO] Compiling 301 source files to /«PKGBUILDDIR»/target/classes
> [INFO] [antrun:run {execution: ant-phase-compile}]
> [INFO] Executing tasks
>
> main:
>
> execute:
> [propertyfile] Creating new property file: /«PKGBUILDDIR»/target/classes/checkstylecompilation.properties
> [javadoc] Generating Javadoc
> [javadoc] Javadoc execution
> [javadoc] warning: [options] bootstrap class path not set in conjunction with -source 1.5
> [javadoc] Loading source file /«PKGBUILDDIR»/src/checkstyle/com/puppycrawl/tools/checkstyle/api/TokenTypes.java...
> [javadoc] Constructing Javadoc information...
> [javadoc] 1 warning
> [INFO] ------------------------------------------------------------------------
> [ERROR] BUILD ERROR
> [INFO] ------------------------------------------------------------------------
> [INFO] An Ant BuildException has occured: The following error occurred while executing this line:
> /«PKGBUILDDIR»/ant-phase-compile.xml:14: java.lang.NullPointerException
> around Ant part ...<ant antfile="ant-phase-compile.xml"></ant>... @ 7:40 in /«PKGBUILDDIR»/target/antrun/build-main.xml
>
> [INFO] ------------------------------------------------------------------------
> [INFO] For more information, run Maven with the -e switch
> [INFO] ------------------------------------------------------------------------
> [INFO] Total time: 24 seconds
> [INFO] Finished at: Thu Jan 16 15:43:02 UTC 2014
> [INFO] Final Memory: 19M/85M
> [INFO] ------------------------------------------------------------------------
> make: *** [mvn-build] Error 1

The full build log is available from:
   http://aws-logs.debian.net/ftbfs-logs/2014/01/14/checkstyle_5.6-2_unstable.log

A list of current common problems and possible solutions is available at
http://wiki.debian.org/qa.debian.org/FTBFS . You're welcome to contribute!

About the archive rebuild: The rebuild was done on EC2 VM instances from
Amazon Web Services, using a clean, minimal and up-to-date chroot. Every
failed build was retried once to eliminate random failures.