How to spawn unmerging items.

Location spawnLocation = origin.clone();
ItemStack itemStack;
World world = ((CraftWorld) spawnLocation.getWorld()).getHandle();
net.minecraft.server.v1_8_R3.ItemStack nmsItemStack = CraftItemStack.asNMSCopy(itemStack);
Field maxStack = null;
try {
    maxStack = getField(itemStack.getItem().getClass(), "maxStackSize");
} catch (NoSuchFieldException e) {
    e.printStackTrace();
}
maxStack.setAccessible(true);
try {
    maxStack.setInt(itemStack.getItem(), 1);
} catch (IllegalAccessException e) {
    e.printStackTrace();
}
EntityItem itemEnt = new EntityItem(world, origin.getX(), spawnLocation.getY(), spawnLocation.getZ(), nmsItemStack);
world.addEntity(itemEnt, CreatureSpawnEvent.SpawnReason.CUSTOM);