SpyglassEnchantmentTarget

import net.minecraft.enchantment.EnchantmentTarget;
import net.minecraft.item.Item;
import net.minecraft.item.Items;
import org.spongepowered.asm.mixin.Mixin;
import org.spongepowered.asm.mixin.Shadow;

public class SpyGlassEnchantmentTarget extends EnchantmentTargetMixin {
    @Override
    public boolean isAcceptableItem(Item item) {
        return item == Items.SPYGLASS;
    }
}

@Mixin(EnchantmentTarget.class)
abstract class EnchantmentTargetMixin {
    @Shadow
    public abstract boolean isAcceptableItem(Item item);
}