@Override
        public String toString() {
            if (allPlatforms != null) {
                return "KeyBinding [allPlatforms=" + allPlatforms + "]";
            }
            return "KeyBinding [mac=" + mac + ", exceptMac=" + exceptMac + "]";
        }
Constructor for separate key bindings for Mac and other platforms.

@param exceptMac key bindings for all other than Mac (e.g. "shift-esc|ctrl-`")
@param mac       key bindings for Mac (e.g. "Command+Alt+C")
stroom-core-client-widget/src/main/java/edu/ycp/cs/dh/acegwt/client/ace/AceCommandDescription.java