private void readObject(final ObjectInputStream s) throws IOException, ClassNotFoundException {
        s.defaultReadObject();
        level = s.readInt();
        syslogEquivalent = s.readInt();
        levelStr = s.readUTF();
        if (levelStr == null) {
            levelStr = "";
        }
    }
Custom deserialization of Level.

@param s serialization stream.
@throws IOException            if IO exception.
@throws ClassNotFoundException if class not found.
log4j-over-slf4j/src/main/java/org/apache/log4j/Level.java