POST request using form-data in body with core java, getting bad request - httpurlconnection

Question

I have written an core java code to post call with form-data(always pdf) along with Auth but i am always getting bad request.enter image description here
public class POSTAPIClientSucessFile2 {
public static void main(String[] args) throws IOException {
try {
String boundary = "";
final String LINE_FEED = "\r\n";
HttpURLConnection httpConn;
OutputStream outputStream;
PrintWriter writer;
String authData = "Bearer 3AAABLblqZhAmXYU1afunO0RBkBBOxDcE0elkSXa6WmNorjjNNGoWjQF5f_mnl21GVK4bOGjsIzqNNB1ZLLLZol--21hmnI1w";
// creates a unique boundary based on time stamp
boundary = "===" + System.currentTimeMillis() + "===";
URL url = new URL("https://api.na3.echosign.com/api/rest/v6/transientDocuments");
System.out.println("URL : " + url.toString());
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.addRequestProperty("Authorization", authData);
outputStream = httpConn.getOutputStream();
writer = new PrintWriter(new OutputStreamWriter(outputStream, "UTF-8"), true);
String fileName = "C:/delete/test.pdf";
//String fieldName = "File";
writer.append("--" + boundary).append(LINE_FEED);
writer.append("Content-Disposition: form-data; name=\"File\"; filename=\"/C:/delete/test.pdf\"").append(LINE_FEED);
writer.append("Content-Type: application/pdf").append(LINE_FEED);
writer.append("Content-Transfer-Encoding: binary").append(LINE_FEED);
writer.append(LINE_FEED);
writer.flush();
int responseCode = ((HttpURLConnection) httpConn).getResponseCode();
System.out.println("responseCode --> "+responseCode);
System.out.println("response msg--> "+((HttpURLConnection) httpConn).getResponseMessage());
System.out.println("response --> "+((HttpURLConnection) httpConn).toString());
FileInputStream inputStream = new FileInputStream(fileName);
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();
} catch (Exception e) {
e.printStackTrace();
}
}
}
always getting bad request even by changing the content-type
enter image description here