Broken links addon test depends on internal Sun API

One of the unit tests in the broken links addon depends on an internal Sun API class.

Steps to reproduce:
1. checkout addon-brokenlinks trunk
2. mvn clean install

Expected: no warnings
Actual: the following warnings are logged:

[WARNING] /home/mathijs/projects/hippo/addon-brokenlinks/repository/src/test/java/org/onehippo/cms7/brokenlinks/ParseTextsTest.java:[24,49] com.sun.org.apache.xerces.internal.parsers.DOMParser is Sun proprietary API and may be removed in a future release
[WARNING] /home/mathijs/projects/hippo/addon-brokenlinks/repository/src/test/java/org/onehippo/cms7/brokenlinks/ParseTextsTest.java:[179,12] com.sun.org.apache.xerces.internal.parsers.DOMParser is Sun proprietary API and may be removed in a future release
[WARNING] /home/mathijs/projects/hippo/addon-brokenlinks/repository/src/test/java/org/onehippo/cms7/brokenlinks/ParseTextsTest.java:[179,35] com.sun.org.apache.xerces.internal.parsers.DOMParser is Sun proprietary API and may be removed in a future release