RTOS/MSP-EXP432E401Y: Simple GPIO Callback question; adding a function to the GPIO config structure

   GPIO_init();
    // install Button callback
    //GPIO_setCallback(Board_GPIO_MYBUTTON, gpioButtonFxn0);

    // Enable interrupts
    GPIO_enableInt(Board_GPIO_MYBUTTON);

GPIO_PinConfig gpioPinConfigs[] = {
// ......
    GPIOMSP432E4_PP2 | GPIO_CFG_IN_PU | GPIO_CFG_IN_INT_RISING,  
// ....

};

/*
 * Array of callback function pointers
 * NOTE: The order of the pin configurations must coincide with what was
 *       defined in MSP_EXP432E401Y.h
 * NOTE: Pins not used for interrupts can be omitted from callbacks array to
 *       reduce memory usage (if placed at end of gpioPinConfigs array).
 */
GPIO_CallbackFxn gpioCallbackFunctions[] = {
    NULL,  /* MSP_EXP432E401Y_USR_SW1 */
    NULL,   /* MSP_EXP432E401Y_USR_SW2 */

    // What TO ADD HERE ? and how to add an index to this callback function?

};