When building openoffice-2.1.0 with java support, it appears that dev-java/xalan already requires >=dev-java/xerces-2.7 and =dev-java/xml-commons-external-1.3* so they are somewhat redundant in the openoffice-2.1.0 ebuild.
Relying on dependencies of other ebuilds is plain unreliable, really don't see what's your problem here.
(In reply to comment #1) > Relying on dependencies of other ebuilds is plain unreliable, really don't see > what's your problem here. > I agree here, so closing.