make sure empty object can be serialize via to_pem

this is mainly to match the specs/tests for the edge case that
the CRL or PKCS10Request are empty object (created with new and without
data)

fixes #21

Sponsored by Lookout Inc.

Author: mkristian

src/main/java/org/jruby/ext/openssl/X509CRL.java

@@ -324,7 +324,7 @@ public IRubyObject initialize_copy(final IRubyObject obj) {
     public IRubyObject to_pem(final ThreadContext context) {
         StringWriter writer = new StringWriter();
         try {
-            PEMInputOutput.writeX509CRL(writer, getCRL());
+            PEMInputOutput.writeX509CRL(writer, crl);
             return RubyString.newString(context.runtime, writer.getBuffer());
         }
         catch (IOException e) {

src/main/java/org/jruby/ext/openssl/impl/PKCS10Request.java

@@ -32,7 +32,6 @@
 import java.io.IOException;
 import java.math.BigInteger;
 import java.util.ArrayList;
-
 import java.security.KeyFactory;
 import java.security.PrivateKey;
 import java.security.PublicKey;
@@ -48,6 +47,7 @@
 
 import org.bouncycastle.asn1.ASN1Sequence;
 import org.bouncycastle.asn1.ASN1Set;
+import org.bouncycastle.asn1.DLSequence;
 import org.bouncycastle.asn1.x500.X500Name;
 import org.bouncycastle.pkcs.PKCS10CertificationRequest;
 import org.bouncycastle.pkcs.PKCS10CertificationRequestBuilder;
@@ -69,7 +69,6 @@
 import org.bouncycastle.operator.ContentVerifierProvider;
 import org.bouncycastle.operator.DefaultSignatureAlgorithmIdentifierFinder;
 import org.bouncycastle.pkcs.PKCSException;
-
 import org.jruby.ext.openssl.SecurityHelper;
 
 public class PKCS10Request {
@@ -169,7 +168,8 @@ private static SubjectPublicKeyInfo makePublicKeyInfo(PublicKey publicKey) {
 
     public ASN1Sequence toASN1Structure() {
         if ( signedRequest == null ) {
-            throw new IllegalStateException("request not signed");
+            // return an empty Sequence
+            return new DLSequence();
         }
         return ASN1Sequence.getInstance( signedRequest.toASN1Structure() );
     }