#fixed code
                             @Override
	public void encodeChildren(FacesContext context) throws IOException {
		if (!TRUE.equals(getApplicationAttribute(context, Socket.class.getName()))) {
			throw new IllegalStateException(ERROR_ENDPOINT_NOT_ENABLED);
		}

		String channel = getChannel();

		if (channel == null || !PATTERN_CHANNEL.matcher(channel).matches()) {
			throw new IllegalArgumentException(String.format(ERROR_INVALID_CHANNEL, channel));
		}

		boolean connected = isConnected();
		Boolean switched = hasSwitched(context, channel, connected);
		String script = null;

		if (switched == null) {
			Integer port = getPort();
			String host = (port != null ? ":" + port : "") + getRequestContextPath(context);
			String channelId = getReference(SocketChannelManager.class).register(channel, getScope(), getUser());
			String functions = getOnopen() + "," + getOnmessage() + "," + getOnclose();
			script = String.format(SCRIPT_INIT, host, channelId, functions, getBehaviorScripts(), connected);
		}
		else if (switched) {
			script = String.format(connected ? SCRIPT_OPEN : SCRIPT_CLOSE, channel);
		}

		if (script != null) {
			context.getResponseWriter().write(script);
		}

		rendered = super.isRendered();
	}
#vulnerable code 
                             @Override
	public void encodeChildren(FacesContext context) throws IOException {
		if (!TRUE.equals(getApplicationAttribute(context, Socket.class.getName()))) {
			throw new IllegalStateException(ERROR_ENDPOINT_NOT_ENABLED);
		}

		String channel = getChannel();

		if (channel == null || !PATTERN_CHANNEL.matcher(channel).matches()) {
			throw new IllegalArgumentException(String.format(ERROR_INVALID_CHANNEL, channel));
		}

		boolean connected = isConnected();
		Boolean switched = hasSwitched(context, channel, connected);
		String script = null;

		if (switched == null) {
			Integer port = getPort();
			String host = (port != null ? ":" + port : "") + getRequestContextPath(context);
			String channelId = getReference(SocketChannelManager.class).register(channel, getScope(), getUser());
			String functions = getOnopen() + "," + getOnmessage() + "," + getOnclose();
			script = String.format(SCRIPT_INIT, host, channelId, functions, getBehaviorScripts(), connected);
		}
		else if (switched) {
			script = String.format(connected ? SCRIPT_OPEN : SCRIPT_CLOSE, channel);
		}

		if (script != null) {
			context.getResponseWriter().write(script);
		}
	} 
                            #location 20 
                            #vulnerability type NULL_DEREFERENCE