NPE in MimeMultipart

I ran into a NullPointerException in MimeMultipart when using GNU 
JavaMail with Apache Axis. This minor diff fixes the problem and is in 
accordance with the handling of a null parts field in javax.mail.Multipart.

   -- Archit

Index: source/javax/mail/internet/MimeMultipart.java
===================================================================
RCS file: 
/cvsroot/classpathx/mail/source/javax/mail/internet/MimeMultipart.java,v
retrieving revision 1.17
diff -u -r1.17 MimeMultipart.java
--- source/javax/mail/internet/MimeMultipart.java       14 Jun 2005 
18:12:59 -0000      1.17
+++ source/javax/mail/internet/MimeMultipart.java       15 Jul 2005 
15:43:36 -0000
@@ -183,6 +183,9 @@
    protected void updateHeaders()
      throws MessagingException
    {
+    if (parts == null)
+      return;
+
      synchronized (parts)
      {
        int len = parts.size();