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"/>
e='10' name='q' value=''/>
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</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=37586ace348287311f2311906b239fba2cd291d7'>root</a>/<a href='/guix/log/gnu?id=37586ace348287311f2311906b239fba2cd291d7'>gnu</a>/<a href='/guix/log/gnu/packages?id=37586ace348287311f2311906b239fba2cd291d7'>packages</a>/<a href='/guix/log/gnu/packages/sssd.scm?id=37586ace348287311f2311906b239fba2cd291d7'>sssd.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/gnu/packages/sssd.scm?id=37586ace348287311f2311906b239fba2cd291d7&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-07-13 17:58:38 +0200'>2023-07-13</span></td><td><a href='/guix/commit/gnu/packages/sssd.scm?id=5594f4c999a71427d7aad9898d7e614b8dbd6b3a'>gnu: sssd: Update to 2.9.1.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/sssd.scm (sssd): Update to 2.9.1.
[native-inputs]: Add bc.
* gnu/packages/patches/sssd-system-directories.patch: Adjust for new version.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Timotej Lazar</td></tr>
<tr><td><span title='2023-05-19 16:46:34 +0200'>2023-05-19</span></td><td><a href='/guix/commit/gnu/packages/sssd.scm?id=f1400fe08fcb2500028f83df999d5e9c7f67f219'>gnu: sssd: Fix build</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/sssd.scm (sssd) [native-inputs]: Add python-toolchain.
[ensure-no-mtimes-pre-1980]: New phase.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Brian Cully</td></tr>
<tr><td><span title='2023-05-19 16:46:34 +0200'>2023-05-19</span></td><td><a href='/guix/commit/gnu/packages/sssd.scm?id=379432f410e868eaf7a4937ecebd9bd16ffecab0'>gnu: sssd: Fix failing tests by using samba/pinned input</a><span class='msg-avail'>...<span class='msg-tooltip'>The latest samba package (4.18.1) causes a SIGABRT in ad_common_tests and
ad_gpo_tests. The pinned version (4.17.0) allows them to succeed, so use that
instead.

* gnu/packages/sssd.scm (sssd) [inputs]: Change samba to samba/pinned.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Brian Cully</td></tr>
<tr><td><span title='2023-04-21 00:44:07 -0400'>2023-04-21</span></td><td><a href='/guix/commit/gnu/packages/sssd.scm?id=09cc2636ef46d96df5a83e9034083e79e02a049b'>gnu: adcli: Add zlib.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/sssd.scm (adcli) [inputs]: Add zlib.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2023-04-21 00:44:07 -0400'>2023-04-21</span></td><td><a href='/guix/commit/gnu/packages/sssd.scm?id=8f0a110503a1936d60f24feec2ebdcb89e502b91'>gnu: adcli: Delete use-local-docbook phase.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/sssd.scm (adcli) [arguments]: Delete use-local-docbook phase.
[native-inputs]: Replace docbook-xml with docbook-xml-4.3.  Add libxml2.
</span></span></td><td>Maxim Cournoyer</td></tr>