Where did XMPPConnection.DEBUG_ENABLED go?

I've been working with the Smack 4.0.0-rc2 release candidate, and am trying to get the basic debug console working.  The documentation explaining how to enable the debug console suggests setting the following:

     XMPPConnection.DEBUG_ENABLED = true;

but actually it seems that this DEBUG_ENABLED static field no longer exists on XMPPConnection in 4.0.  I tried the other documented means for enabling the debug console, like setting the command-line parameter:

          -Dsmack.debugEnabled=true

but this also didn't seem to work. 

Can anyone provide advice on how to enable the debug console in Smack 4.0?

Thanks!