Multipart/form-data vk api

String url_to_send = upload_url+
                            "&mid=" +mid+
                            "&aid=" +aid+
                            "&hash="+hash+
                            "&rhash="+rhash+
                            "&swfupload=1"+
                            "&api=1"+
                            "&wallphoto=1";

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;
 
public class MultipartUtility {
    private final String boundary;
    private static final String LINE_FEED = "\r\n";
    private HttpURLConnection httpConn;
    private String charset;
    private OutputStream outputStream;
    private PrintWriter writer;
 
    /**
     * This constructor initializes a new HTTP POST request with content type
     * is set to multipart/form-data
     * @param requestURL
     * @param charset
     * @throws IOException
     */
    public MultipartUtility(String requestURL, String charset)
            throws IOException {
        this.charset = charset;
 
        // creates a unique boundary based on time stamp
        boundary = "===" + System.currentTimeMillis() + "===";
 
        URL url = new URL(requestURL);
        httpConn = (HttpURLConnection) url.openConnection();
        httpConn.setUseCaches(false);
        httpConn.setDoOutput(true); // indicates POST method
        httpConn.setDoInput(true);
        httpConn.setRequestProperty("Content-Type",
                "multipart/form-data; boundary=" + boundary);
        httpConn.setRequestProperty("User-Agent", "CodeJava Agent");
        httpConn.setRequestProperty("Test", "Bonjour");
        outputStream = httpConn.getOutputStream();
        writer = new PrintWriter(new OutputStreamWriter(outputStream, charset),
                true);
    }
 
    /**
     * Adds a form field to the request
     * @param name field name
     * @param value field value
     */
    public void addFormField(String name, String value) {
        writer.append("--" + boundary).append(LINE_FEED);
        writer.append("Content-Disposition: form-data; name="" + name + """)
                .append(LINE_FEED);
        writer.append("Content-Type: text/plain; charset=" + charset).append(
                LINE_FEED);
        writer.append(LINE_FEED);
        writer.append(value).append(LINE_FEED);
        writer.flush();
    }
 
    /**
     * Adds a upload file section to the request
     * @param fieldName name attribute in <input type="file" name="..." />
     * @param uploadFile a File to be uploaded
     * @throws IOException
     */
    public void addFilePart(String fieldName, File uploadFile)
            throws IOException {
        String fileName = uploadFile.getName();
        writer.append("--" + boundary).append(LINE_FEED);
        writer.append(
                "Content-Disposition: form-data; name="" + fieldName
                        + ""; filename="" + fileName + """)
                .append(LINE_FEED);
        writer.append(
                "Content-Type: "
                        + URLConnection.guessContentTypeFromName(fileName))
                .append(LINE_FEED);
        writer.append("Content-Transfer-Encoding: binary").append(LINE_FEED);
        writer.append(LINE_FEED);
        writer.flush();
 
        FileInputStream inputStream = new FileInputStream(uploadFile);
        byte[] buffer = new byte[4096];
        int bytesRead = -1;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }
        outputStream.flush();
        inputStream.close();
 
        writer.append(LINE_FEED);
        writer.flush();
    }
 
    /**
     * Adds a header field to the request.
     * @param name - name of the header field
     * @param value - value of the header field
     */
    public void addHeaderField(String name, String value) {
        writer.append(name + ": " + value).append(LINE_FEED);
        writer.flush();
    }
 
    /**
     * Completes the request and receives response from the server.
     * @return a list of Strings as response in case the server returned
     * status OK, otherwise an exception is thrown.
     * @throws IOException
     */
    public List<String> finish() throws IOException {
        List<String> response = new ArrayList<String>();
 
        writer.append(LINE_FEED).flush();
        writer.append("--" + boundary + "--").append(LINE_FEED);
        writer.close();
 
        // checks server's status code first
        int status = httpConn.getResponseCode();
        if (status == HttpURLConnection.HTTP_OK) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    httpConn.getInputStream()));
            String line = null;
            while ((line = reader.readLine()) != null) {
                response.add(line);
            }
            reader.close();
            httpConn.disconnect();
        } else {
            throw new IOException("Server returned non-OK status: " + status);
        }
 
        return response;
    }
}

String charset = "UTF-8";
        File uploadFile1 = new File("C:\\test.png");
        String requestURL = url_to_send +"&access_token="+TOKEN;        // пробовал и с токеном и без него - результат один...
 
        try {
            MultipartUtility multipart = new MultipartUtility(requestURL, charset);
 
            //multipart.addHeaderField("User-Agent", "CodeJava");
            //multipart.addHeaderField("Test-Header", "Header-Value");
 
            //multipart.addFormField("description", "Cool Pictures");
            //multipart.addFormField("keywords", "Java,upload,Spring");
 
            multipart.addFilePart("photo", uploadFile1);
            //multipart.addFilePart("fileUpload", uploadFile2);
 
            List<String> response = multipart.finish();
 
            System.out.println("SERVER REPLIED:");
 
            for (String line : response) { System.out.println(line); }
        } catch (IOException ex) { System.err.println(ex); }