Drop item

Hello I want to know how to set when a player break a block it drops a random item like lucky block?

PHP:

function onBreak(BlockBreakEvent $ev){
    switch($ev->getBlock()->getId()){
        case 1: //If break Block ID 1
            $ev->setDrops(/* Drop Block or Item Here */);
        break;
    }
}


Example,

PHP:

function onBreak(BlockBreakEvent $ev){
    switch($ev->getBlock()->getId()){
        case 1:
            $ev->setDrops(array(Block::get(mt_rand(1,20),0,1))); //Drop 1 Block which id is 1 to 20 (random)
        break;
    }
}


Thank you