Getting 400 Bad requestion while connecting to RQM via API

RQM connection is successful after that adding header and trying to POST gives error.
the request body is an xml, and the xml is converted and given as input stream.attached the code below. Kindly help in solving the issue.

for the connection.doPost(fis, l, "xml"); i have tried all the combinations for content type like application/xml, XML, .xml and text/xml. while debugging inside the api methods i found the response of execute method is given 400 . till that the execution and the URI receiving happens correctly.

try {

      connection = rawRestServiceClient.getConnection(uri);

 

      connection.addRequestHeader("Slug", "49");

      connection.addRequestHeader("Referer", "https://rb-alm-05-d.de.bosch.com/qm");

      connection.addRequestHeader("Content-Type", "application/xml");

      connection.addRequestHeader("Accept", "application/xml");

      InputStream fis = null;

      ByteArrayOutputStream os = new ByteArrayOutputStream();

      int b;

 

      try {

        fis = new FileInputStream(

            new File("C:\\temp\\vid3cob\\workspace\\orion\\8.0.1\\workspace\\com.bosch.almmig.reqone\\Testplan.xml"));

      }

      catch (FileNotFoundException e) {

        // TODO Auto-generated catch block

        LOGGER.error("Rqone query prefix is not encoded properly", e);

      }

      try {

        if (fis != null) {

 

          while ((b = fis.read()) != -1) {

            os.write(b);

          }

          // connection.doGet();

          Long l = new Long(os.size());

          // connection.doPost(fis, l, "xml");

 

          connection.doPost(fis, l, "xml");

        }