Java - Signature ( firma formateado ) alguien sabe. (SIN FORMATO XML)

Transformer trans = tf.newTransformer();

trans.setOutputProperty(OutputKeys.INDENT, "yes");

Reference ref = fac.newReference

 ("", fac.newDigestMethod(DigestMethod.SHA1, null),

  Collections.singletonList

   (fac.newTransform

    (Transform.ENVELOPED, (TransformParameterSpec) null)),

     null, null);

// Create the SignedInfo.

SignedInfo si = fac.newSignedInfo

 (fac.newCanonicalizationMethod

  (CanonicalizationMethod.INCLUSIVE,

   (C14NMethodParameterSpec) null),

    fac.newSignatureMethod(SignatureMethod.RSA_SHA1, null),

     Collections.singletonList(ref));

KeyStore ks = KeyStore.getInstance("JKS");

ks.load(new FileInputStream("mykeystore.jks"), "changeit".toCharArray());

KeyStore.PrivateKeyEntry keyEntry =

    (KeyStore.PrivateKeyEntry) ks.getEntry

        ("mykey", new KeyStore.PasswordProtection("changeit".toCharArray()));

X509Certificate cert = (X509Certificate) keyEntry.getCertificate();

// Create the KeyInfo containing the X509Data.

KeyInfoFactory kif = fac.getKeyInfoFactory();

List x509Content = new ArrayList();

x509Content.add(cert.getSubjectX500Principal().getName());

x509Content.add(cert);

X509Data xd = kif.newX509Data(x509Content);

KeyInfo ki = kif.newKeyInfo(Collections.singletonList(xd));

// Instantiate the document to be signed.

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

dbf.setNamespaceAware(true);

Document doc = dbf.newDocumentBuilder().parse

    (new FileInputStream("purchaseOrder.xml"));

// Create a DOMSignContext and specify the RSA PrivateKey and

// location of the resulting XMLSignature's parent element.

DOMSignContext dsc = new DOMSignContext

    (keyEntry.getPrivateKey(), doc.getDocumentElement());

// Create the XMLSignature, but don't sign it yet.

XMLSignature signature = fac.newXMLSignature(si, ki);

//Generando la firma 

signature.sign(dsc);

// y despues genero el documento xml  pero me queda todo sin salto de linea.

OutputStream os = new FileOutputStream("signedPurchaseOrder.xml");

TransformerFactory tf = TransformerFactory.newInstance();

Transformer trans = tf.newTransformer();

trans.transform(new DOMSource(doc), new StreamResult(os));