Fixing build.

- When we moved to the latest version of bouncycastle, it looks like I
  forgot this particular instance.

Change-Id: I9822187707f4644250beed4817f03dc6401adfe3
diff --git a/java/src/com/google/polo/ssl/CsrUtil.java b/java/src/com/google/polo/ssl/CsrUtil.java
index d5ff7bc..f399dc4 100644
--- a/java/src/com/google/polo/ssl/CsrUtil.java
+++ b/java/src/com/google/polo/ssl/CsrUtil.java
@@ -7,11 +7,11 @@
 import org.bouncycastle.asn1.x509.GeneralNames;
 import org.bouncycastle.asn1.x509.KeyPurposeId;
 import org.bouncycastle.asn1.x509.KeyUsage;
+import org.bouncycastle.asn1.x509.SubjectKeyIdentifier;
 import org.bouncycastle.asn1.x509.X509Extensions;
 import org.bouncycastle.asn1.x509.X509Name;
 import org.bouncycastle.x509.X509V3CertificateGenerator;
 import org.bouncycastle.x509.extension.AuthorityKeyIdentifierStructure;
-import org.bouncycastle.x509.extension.SubjectKeyIdentifierStructure;
 
 import java.math.BigInteger;
 import java.security.GeneralSecurityException;
@@ -83,7 +83,7 @@
 
         certGen.addExtension(X509Extensions.AuthorityKeyIdentifier, true, authIdentifier);
         certGen.addExtension(X509Extensions.SubjectKeyIdentifier, true,
-                new SubjectKeyIdentifierStructure(rootPair.getPublic()));
+                SubjectKeyIdentifier.getInstance(rootPair.getPublic().getEncoded()));
 
         certGen.addExtension(X509Extensions.SubjectAlternativeName, false, new GeneralNames(
                 new GeneralName(GeneralName.rfc822Name, EMAIL)));
@@ -139,7 +139,7 @@
                 new AuthorityKeyIdentifierStructure(rootCert));
         // Use provided public key for the subject
         certGen.addExtension(X509Extensions.SubjectKeyIdentifier, false,
-                new SubjectKeyIdentifierStructure(publicKey));
+                SubjectKeyIdentifier.getInstance(publicKey.getEncoded()));
         // This is not a CA certificate, do not allow
         certGen.addExtension(X509Extensions.BasicConstraints, true, new BasicConstraints(false));
         // This can be used for signature and encryption