Patch for review: Fix CapTPReplacer NPE on a promise for null.

I'd like your opinion on this before I commit it to SVN. I'm not an expert on the JOSS CapTP components, but this bug and fix seemed pretty clear.

commit b113b90299f16ef65c8d6e55b2f6c5e2da966e14
Author: Kevin Reid <kpreid-M/[email protected]>
Date:   Fri Aug 12 09:32:11 2011

    Fix CapTPReplacer NPE on a promise for null.
    
    If CapTPReplacer met a promise resolved to null, it would crash with NullPointerException when trying to check for a writeReplace method. Fix by adding a shortcut around that code for null.

diff --git a/src/jsrc/net/captp/jcomm/CapTPReplacer.java b/src/jsrc/net/captp/jcomm/CapTPReplacer.java
index 53487c0..d8191a7 100644
--- a/src/jsrc/net/captp/jcomm/CapTPReplacer.java
+++ b/src/jsrc/net/captp/jcomm/CapTPReplacer.java
@@ -54,7 +54,10 @@ class CapTPReplacer extends Replacer {
      */
     public Object substitute(Object ref) {
         Object resolvedRef = Ref.resolution(ref);
-        if (resolvedRef != ref) {
+        if (resolvedRef == null) {
+            // Next branch would NullPointerException, so don't try.
+            ref = resolvedRef;
+        } else if (resolvedRef != ref) {
             /* Java serialization has given the original ref the chance to
              * writeReplace itself, but not the target. Do that now.
              */

-- 
Kevin Reid                                  <http://switchb.org/kpreid/>