Default Proxy Java

Question

I'm trying to call Webservices API using JAVA but I have connection issue probably due to a proxy.

I already did it with C# WPF application, and to avoid connection issue I set following option on App.config file

<system.net>
   <defaultProxy useDefaultCredentials="true"></defaultProxy>

I don't find a way to do the same setup on JAVA and my connection is rejected :

Do you know how can I setup the default proxy ?

JAVA code

/**
 * Executes the request and returns its response.
 *
 * @return the request's response
 * @throws IOException if the underlying {@link HttpsURLConnection} could
 *         not be set up or executed
 */
public String execute() throws IOException {
    HttpsURLConnection connection = null;
    try {
        connection = (HttpsURLConnection) url.openConnection();
        connection.setRequestMethod("POST");


        // write POST data to request
        // Exception is raised at this level
        if (postData != null && !postData.toString().isEmpty()) {

            connection.setDoOutput(true);

            try (OutputStreamWriter out = new OutputStreamWriter(connection.getOutputStream())) 
            {
                out.write(postData.toString());
            }
            catch(Exception e){
                System.out.println(e.getMessage());
            }
        }

        // execute request and read response
        try (BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()))) {

            StringBuilder response = new StringBuilder();
            String line;

            while ((line = in.readLine()) != null) {
                response.append(line);
            }

            return response.toString();
        }
    }
    finally {
        connection.disconnect();
    }
}

Many thanks for your help