src/main/java/org/intellimate/izou/sdk/frameworks/music/player/template/CommandHandler.java
public void setNextPreviousController(Consumer<String> controller) {
        if (controller == null)
            return;
        nextPrevious = controller;
        capabilities.setNextPrevious(true);
    }
public void setNextPreviousController(Consumer<String> controller) {
        if (controller == null)
            return;
        nextPrevious = controller;
        capabilities.setNextPrevious(true);
    }
adds the ability to select the next/previous track
@param controller  the controller for callback