Reentrancy problem in generateBranchId()

Under heavy load I have been having problems with 
generateBranchId() throwing the following exception:

java.lang.ArrayIndexOutOfBoundsException
	at java.lang.System.arraycopy(Native Method)
	at 
sun.security.provider.DigestBase.engineUpdate(DigestBase.java:102)
	at sun.security.provider.MD5.implDigest(MD5.java:100)
	at 
sun.security.provider.DigestBase.engineDigest(DigestBase.java:161)
	at 
sun.security.provider.DigestBase.engineDigest(DigestBase.java:140)
	at 
java.security.MessageDigest$Delegate.engineDigest(MessageDigest.java:531)
	at 
java.security.MessageDigest.digest(MessageDigest.java:309)
	at 
java.security.MessageDigest.digest(MessageDigest.java:355)
	at 
gov.nist.javax.sip.Utils.generateBranchId(Utils.java:151)
	at 
gov.nist.javax.sip.SipProviderImpl.getNewClientTransaction(SipProviderImpl.java:349)
	at uas.Server.processAck(Server.java:75)
	at uas.Server.processRequest(Server.java:54)
	at 
gov.nist.javax.sip.EventScanner.deliverEvent(EventScanner.java:219)
	at 
gov.nist.javax.sip.SipProviderImpl.handleEvent(SipProviderImpl.java:148)
	at 
gov.nist.javax.sip.DialogFilter.processRequest(DialogFilter.java:902)
	at 
gov.nist.javax.sip.stack.SIPServerTransaction.processRequest(SIPServerTransaction.java:758)
	at 
gov.nist.javax.sip.stack.UDPMessageChannel.run(UDPMessageChannel.java:403)
	at java.lang.Thread.run(Thread.java:613)

By declaring the method to be "synchronized", the problem 
appears to have been resolved.  Here is the diff:

Index: Utils.java
===================================================================
RCS file: 
/cvs/jain-sip/src/gov/nist/javax/sip/Utils.java,v
retrieving revision 1.13
diff -r1.13 Utils.java
146c146
<       public static String generateBranchId() {
---
>       public static synchronized String generateBranchId() {


-Mardy