8081744: Clear out list corner case

Reviewed-by: mullan, rhalade

src/share/classes/sun/security/provider/certpath/RevocationChecker.java

@@ -1041,12 +1041,9 @@ class RevocationChecker extends PKIXRevocationChecker {
                 boolean signFlag = true;
                 List<? extends Certificate> cpList =
                     cpbr.getCertPath().getCertificates();
-                if (cpList.isEmpty()) {
-                    return;
-                }
                 try {
-                    for (int i = cpList.size()-1; i >= 0; i-- ) {
-                        X509Certificate cert = (X509Certificate)cpList.get(i);
+                    for (int i = cpList.size() - 1; i >= 0; i--) {
+                        X509Certificate cert = (X509Certificate) cpList.get(i);
 
                         if (debug != null) {
                             debug.println("RevocationChecker.buildToNewKey()"
@@ -1073,8 +1070,10 @@ class RevocationChecker extends PKIXRevocationChecker {
                 // If it doesn't check out, try to find a different key.
                 // And if we can't find a key, then return false.
                 PublicKey newKey = cpbr.getPublicKey();
+                X509Certificate newCert = cpList.isEmpty() ?
+                    null : (X509Certificate) cpList.get(0);
                 try {
-                    checkCRLs(currCert, newKey, (X509Certificate) cpList.get(0),
+                    checkCRLs(currCert, newKey, newCert,
                               true, false, null, params.trustAnchors());
                     // If that passed, the cert is OK!
                     return;