8270797: ShortECDSA.java test is not complete

Backport-of: 221e4b9c61cd1c9c3f4c037589ba639541532910

test/jdk/com/sun/org/apache/xml/internal/security/ShortECDSA.java

@@ -25,9 +25,12 @@
  * @test
  * @bug 8259535
  * @summary ECDSA SignatureValue do not always have the specified length
- * @modules java.xml.crypto
+ * @modules java.xml.crypto/com.sun.org.apache.xml.internal.security
+ *          java.xml.crypto/com.sun.org.apache.xml.internal.security.signature
  */
 
+import com.sun.org.apache.xml.internal.security.Init;
+import com.sun.org.apache.xml.internal.security.signature.XMLSignature;
 import org.w3c.dom.Document;
 import org.w3c.dom.NodeList;
 import org.xml.sax.InputSource;
@@ -91,6 +94,18 @@ public static void main(String[] args) throws Exception {
             System.out.println(HexFormat.ofDelimiter(":").formatHex(sig));
             throw new RuntimeException("Failed");
         }
+
+        // Internal way
+        Init.init();
+        XMLSignature signature = new XMLSignature(document, null,
+                SignatureMethod.ECDSA_SHA256, CanonicalizationMethod.INCLUSIVE);
+        signature.sign(privateKey);
+        sig = signature.getSignatureValue();
+        if (sig.length != 64) {
+            System.out.println("Length: " + sig.length);
+            System.out.println(HexFormat.ofDelimiter(":").formatHex(sig));
+            throw new RuntimeException("Failed");
+        }
     }
 
     public static class XmlSigningUtils {