public String getMac() {
            return mac;
        }
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