libdtdparser-java version 1.21a-4 failed to build with openjdk-7

During a rebuild test on precise with default-jdk switched to openjdk-7, a build failure was detected for libdtdparser-java version 1.21a-4.

See attached log for full build failure details.

This log snippet might also be of interest:

test -x debian/rules
mkdir -p "."
cd . && /usr/lib/jvm/default-java/bin/java -classpath /usr/share/ant/lib/ant.jar:/usr/share/ant/lib/ant-launcher.jar:/usr/lib/jvm/default-java/lib/tools.jar -Dant.home=/usr/share/ant org.apache.tools.ant.Main -Dcompile.debug=true -Dcompile.optimize=true build createdoc
Buildfile: /«PKGBUILDDIR»/build.xml

prepare:
    [mkdir] Created dir: /«PKGBUILDDIR»/dtdparser-1.21/doc
    [mkdir] Created dir: /«PKGBUILDDIR»/classes

build:

compile:
    [javac] /«PKGBUILDDIR»/build.xml:44: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds
    [javac] Compiling 32 source files to /«PKGBUILDDIR»/classes
    [javac] /«PKGBUILDDIR»/source/com/wutka/dtd/Scanner.java:505: error: unmappable character for encoding ASCII
    [javac] //[61] conditionalSect ::= ?includeSect | ignoreSect
    [javac] ^
    [javac] /«PKGBUILDDIR»/source/com/wutka/dtd/Scanner.java:506: error: unmappable character for encoding ASCII
    [javac] //[62] includeSect ::= ?'<![' S? 'INCLUDE' S? '[' extSubsetDecl ']]>'
    [javac] ^
    [javac] /«PKGBUILDDIR»/source/com/wutka/dtd/Scanner.java:507: error: unmappable character for encoding ASCII
    [javac] //[63] ignoreSect ::= ?'<![' S? 'IGNORE' S? '[' ignoreSectContents* ']]>'
    [javac] ^
    [javac] /«PKGBUILDDIR»/source/com/wutka/dtd/Scanner.java:508: error: unmappable character for encoding ASCII
    [javac] //[64] ignoreSectContents ::= ?Ignore ('<![' ignoreSectContents ']]>' Ignore)*
    [javac] ^
    [javac] /«PKGBUILDDIR»/source/com/wutka/dtd/Scanner.java:509: error: unmappable character for encoding ASCII
    [javac] //[65] Ignore ::= ?Char* - (Char* ('<![' | ']]>') Char*)
    [javac] ^
    [javac] /«PKGBUILDDIR»/source/com/wutka/dtd/Scanner.java:528: error: unmappable character for encoding ASCII
    [javac] // has been found. ?Break out of for loop.
    [javac] ^
    [javac] /«PKGBUILDDIR»/source/com/wutka/dtd/Scanner.java:551: error: unmappable character for encoding ASCII
    [javac] // has been found. ?Increment nesting depth.
    [javac] ^
    [javac] 7 errors

BUILD FAILED
/«PKGBUILDDIR»/build.xml:38: The following error occurred while executing this line:
/«PKGBUILDDIR»/build.xml:44: Compile failed; see the compiler error output for details.

Total time: 0 seconds
make: *** [debian/stamp-ant-build] Error 1
dpkg-buildpackage: error: debian/rules build gave error exit status 2
────────────────────────────────────────────────────────────────────────────────
Build finished at 20111111-0045

Finished
────────

E: Build failure (dpkg-buildpackage died)