multipart.addBodyPart(p1);
multipart.addBodyPart(p2);
multipart.addBodyPart(p3);
ByteArrayOutputStream out = new ByteArrayOutputStream();
multipart.writeTo(out);
out.close();
String expected = "\r\n" +
"--foo\r\n" +
"Content-Disposition: form-data; name=\"field1\"\r\n" +