I was getting NPE from Base64.encodeBytes(), as response was null.

So in SASLMechanism.java at line 154, I replaced

        String authenticationText = Base64.encodeBytes(response,Base64.DONT_BREAK_LINES);
        if(authenticationText.equals("")) {
            authenticationText = "=";
        }

with

        String authenticationText = "";
        if( null != response ){
          authenticationText = Base64.encodeBytes(response, Base64.DONT_BREAK_LINES);
        }
        if(authenticationText.equals("")) {
            authenticationText = "=";
        }

and now authentization works.

Ondra Zizka