InputStream entityStream = new ByteArrayInputStream(message);
MultiPartFormMessageBodyReader multiPartFormMBR = new MultiPartFormMessageBodyReader();
MediaType mediaType = MediaType.valueOf("multipart/form-data; boundary=AaB03x");
MultiPartBody multiPartBody = multiPartFormMBR.readFrom(null, null, null, mediaType, null, entityStream);
String[] paramNames = multiPartBody.getParameterNames();
String[] expectedParamNames = {paramName1, paramName2, paramName3};
System.out.println(Arrays.toString(paramNames));
Assert.assertArrayEquals(expectedParamNames, paramNames);