// Context handle is modified by the server (typically zeroed out)
        if (contextHandle == null) {
            contextHandle = new byte[20];
        }
        buf.readOctetArray(contextHandle, 0, 20);
    }

    /**
     * Checks if the context handle has been invalidated (all zeros).
     * A successful unregistration typically results in a zeroed context handle.
     *