The serializer knows of its own package name, not just through hard
references, e.g. import statements, but through "soft" references in Strings.
For example the serializer's CharInfo.java has this code in it:
        public static final String XML_ENTITIES_RESOURCE
                  = "org.apache.xml.serializer.XMLEntities";


When Apache code is repackaged (e.g. by Sun or IBM) it is
sometimes has its package names changed. Repackaging would be
easier and safer if the code in the serializer was not aware of its own package
names in "soft" references in Strings. Hard references are easy to fix
at build time, soft references will show breakage at runtime. It would be
easier for repackagers, and safter if the serializer had not soft references
to its own package name.