server_scripts\botany\gregrubber.js

ServerEvents.recipes(event => {

    event.remove({ id: 'botanytrees:gtceu/rubber' })

    event.recipes.botanypots.crop(
        'gtceu:rubber_sapling', // seed item
        ['minecraft:dirt'], // categories that this crop can be planted on
        { block: 'gtceu:rubber_sapling' }, // display block
        [
            Item.of('gtceu:rubber_log') // item
                .withChance(100) // weight of this entry compared to the others
                .withRolls(2, 4) // the times this loot will be chosen (min, max)
            ,
            Item.of('minecraft:stick') // item
                .withChance(25) // weight of this entry compared to the others
                .withRolls(1, 2) // the times this loot will be chosen (min, max)
            ,
            Item.of('gtceu:rubber_sapling') // item
                .withChance(15) // weight of this entry compared to the others
                .withRolls(1, 2) // the times this loot will be chosen (min, max)
            ,
            Item.of('gtceu:sticky_resin') // item
                .withChance(50) // weight of this entry compared to the others
                .withRolls(2, 4) // the times this loot will be chosen (min, max)
        ],
        10, // growthTicks
        1 // optional, growthModifier - this can be set to 1 in most cases
    )
})