Append parameters to POST in Intercept(OkHttp)

InterceptRequest.java

/**
     * @param parameter - this is string that contains parameters for Http POST
     * @param request - old Request
     * @return - new {@link Request} with additional parameters
     * */
    public static Request interceptRequest(@NotNull Request request, @NotNull String parameter)
            throws IOException {

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        Sink sink = Okio.sink(baos);
        BufferedSink bufferedSink = Okio.buffer(sink);

        /**
         * Write old params
         * */
        request.body().writeTo(bufferedSink);

        /**
         * write to buffer additional params
         * */
        bufferedSink.writeString(parameter, Charset.defaultCharset());

        RequestBody newRequestBody = RequestBody.create(
                request.body().contentType(),
                bufferedSink.buffer().readUtf8()
        );

        return request.newBuilder().post(newRequestBody).build();
    }