This patch eliminates the need for providing "xjavac", which saves building a
package for the unmaintained "xerces-tools".

Taken from https://anonscm.debian.org/viewvc/pkg-java/trunk/libxerces2-java/debian/patches/01_xjavac_taskdef.patch?revision=14507

Index: b/build.xml
===================================================================
--- a/build.xml
+++ b/build.xml
@@ -39,7 +39,7 @@
   <property name="tools.dir" value="./tools"/>
 
   <!-- enable compilation under JDK 1.4 and above -->
-  <taskdef name="xjavac" classname="org.apache.xerces.util.XJavac">
+  <taskdef name="xjavac" classname="org.apache.tools.ant.taskdefs.Javac">
     <classpath>
       <pathelement location="${tools.dir}/bin/xjavac.jar"/>
     </classpath>
@@ -291,7 +291,7 @@
            source="${javac.source}"
            target="${javac.target}"
            classpath="${build.dir}/classes:${tools.dir}/${jar.apis}:${tools.dir}/${jar.resolver}:${tools.dir}/${jar.serializer}"
-           debug="${debug}"
+           debug="${debug}" nowarn="true"
            debuglevel="${debuglevel}"
            deprecation="${deprecation}"
            optimize="${optimize}"
@@ -359,7 +359,7 @@
            source="${javac.source}"
            target="${javac.target}"
            classpath="${build.dir}/classes:${tools.dir}/${jar.apis}"
-           debug="${debug}"
+           debug="${debug}" nowarn="true"
            debuglevel="${debuglevel}"
            includeAntRuntime="false"
            includeJavaRuntime="true"/>
@@ -379,7 +379,7 @@
            source="${javac.source}"
            target="${javac.target}"
            classpath="${tools.dir}/${jar.apis}:${build.dir}/classes:./tools/junit.jar"
-           debug="${debug}"
+           debug="${debug}" nowarn="true"
            debuglevel="${debuglevel}"
            includeAntRuntime="false"
            includeJavaRuntime="true"/>
ge</option>
</select>
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</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=2c5f6787fd50553364922766af8805aff71105e3&amp;showmsg=1'>root</a>/<a href='/guix/log/tests?id=2c5f6787fd50553364922766af8805aff71105e3&amp;showmsg=1'>tests</a>/<a href='/guix/log/tests/egg.scm?id=2c5f6787fd50553364922766af8805aff71105e3&amp;showmsg=1'>egg.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/egg.scm?id=2c5f6787fd50553364922766af8805aff71105e3'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2024-04-15 22:36:42 +0200'>2024-04-15</span></td><td class='logsubject'><a href='/guix/commit/tests/egg.scm?id=54be7795b5cc2f6cad05f8649121372c9d5af806'>utils: Don’t re-export ‘call-with-temporary-output-file’.</a></td><td>Ludovic Courtès</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* guix/utils.scm: Remove re-export of ‘call-with-temporary-output-file’.
Autoload a number of modules.
* guix/download.scm, guix/import/hackage.scm,
guix/import/hexpm.scm, guix/import/opam.scm,
guix/import/pypi.scm, tests/cpio.scm, tests/egg.scm,
tests/opam.scm, tests/publish.scm, tests/store-database.scm,
tests/utils.scm: Adjust imports accordingly.

Change-Id: I3f5e94631397996a30be2ea4ff8b50a3371e8ee7


</td></tr>