Based on https://anonscm.debian.org/viewvc/pkg-java/trunk/libxerces2-java/debian/patches/03_bootclasspath.patch?revision=14509, adopted for guix

--- xerces-2_11_0/build.xml.orig	2010-11-26 21:42:11.000000000 +0100
+++ xerces-2_11_0/build.xml	2017-03-28 14:04:41.946606996 +0200
@@ -290,13 +290,14 @@
            destdir="${build.dest}"
            source="${javac.source}"
            target="${javac.target}"
-           classpath="${build.dir}/classes:${tools.dir}/${jar.apis}:${tools.dir}/${jar.resolver}:${tools.dir}/${jar.serializer}"
+           classpath="${build.dir}/classes:${jar.jaxp}:${jar.apis-ext}:${jar.resolver}"
            debug="${debug}" nowarn="true"
            debuglevel="${debuglevel}"
            deprecation="${deprecation}"
            optimize="${optimize}"
            includeAntRuntime="false"
-           includeJavaRuntime="false"
+           includeJavaRuntime="true"
+           bootclasspath="${jar.jaxp}:${jar.apis-ext}:${jar.resolver}"
            excludes="org/xml/sax/** 
                 javax/xml/**
                 org/w3c/dom/*
@@ -1451,13 +1452,14 @@
                destdir="${build.dest}"
                source="${javac.source}"
                target="${javac.target}"
-               classpath="${build.dir}/classes:${tools.dir}/${jar.apis}:${tools.dir}/${jar.resolver}:${tools.dir}/${jar.serializer}"
+               classpath="${build.dir}/classes:${jar.jaxp}:${jar.apis-ext}:${jar.resolver}"
                debug="${debug}"
                debuglevel="${debuglevel}"
                deprecation="${deprecation}"
                optimize="${optimize}"
                includeAntRuntime="false"
-               includeJavaRuntime="false"
+               includeJavaRuntime="true"
+               bootclasspath="${jar.jaxp}:${jar.apis-ext}:${jar.resolver}"
                excludes="org/xml/sax/** 
                     javax/xml/**
                     org/w3c/dom/*
></table>
<div class='path'>path: <a href='/guix/log/?id=afb82831fa4d8602859eb00056dd3f418ed363c9'>root</a>/<a href='/guix/log/doc?id=afb82831fa4d8602859eb00056dd3f418ed363c9'>doc</a>/<a href='/guix/log/doc/guix.de.texi?id=afb82831fa4d8602859eb00056dd3f418ed363c9'>guix.de.texi</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/doc/guix.de.texi?id=afb82831fa4d8602859eb00056dd3f418ed363c9&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-12-02 23:08:47 +0100'>2018-12-02</span></td><td><a href='/guix/commit/doc/guix.de.texi?id=793dcd8c679cd53e2792cf26d539505fac396d3d'>nls: Update 'de' translation of the manual.</a></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-11-01 12:36:47 +0100'>2018-11-01</span></td><td><a href='/guix/commit/doc/guix.de.texi?id=1e40e70bfebba47ccea354ddf862276d2c4223ea'>doc: Add German translation.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/contributing.de.texi: New file.
* doc/guix.de.texi: New file
* doc/local.mk (TRANSLATED_INFO): Add them.
(info_TEXINFOS): Add guix.de.texi.
* po/doc/guix-manual.de.po: New file.
* po/doc/local.mk (EXTRA_DIST): Add it.
* doc/guix.texi: Document the German translation.
</span></span></td><td>Julien Lepiller</td></tr>