OkHttp okhttp3.MultipartBody.Part transcribed from Kotlin to Java

MultipartBody.java

    // Turns out I didn't need this after all... ;-)

    Headers headers = new Headers.Builder().addUnsafeNonAscii("Content-Disposition", buildContentDispositionHeader("file", file.getName())).add("Content-Type", rb.contentType().toString()).build();
    return Part.create(headers, rb);

    // As in okhttp3.MultipartBody.Part.createFormData(String, String, RequestBody), transcribed from Scala (?)
    private static String buildContentDispositionHeader(String name, String fileName) {
        StringBuilder sb = new StringBuilder("form-data; name=");
        appendQuotedString(sb, name);
        if (fileName != null) {
            sb.append("; filename=");
            appendQuotedString(sb, fileName);
        }
        return sb.toString();
    }

    // As in private okhttp3.MultipartBody.Part.appendQuotedString(), transcribed from Scala (?)
    private static void appendQuotedString(StringBuilder sb, String key) {
        sb.append('"');
        for (int i = 0; i < key.length(); i++) {
            char ch = key.charAt(i);
            switch (ch) {
                case '\n': sb.append("%0A"); break;
                case '\r': sb.append("%0D"); break;
                case '"': sb.append("%22"); break;
                default: sb.append(ch);
            }
        }
        sb.append('"');
    }