public static Class<?> loadClass(final String className) throws ClassNotFoundException {
        return loadClass(null, className);
    }
Reads a Map of Serializable key and value pairs. This method will return
<tt>null</tt> if the Map written to the stream was <tt>null</tt>.

@param in the input stream.
@param map a Map of Serializable key and value pairs.
@param loader class loader to use to build elements inside of the serialized collection.
@throws IOException if an error occurs.
@return the number of elements added to the collection.
xmppserver/src/main/java/org/jivesoftware/util/cache/DefaultExternalizableUtil.java