Prevents generation of any blocks by lava and water merging

ObsidianPreventer.java

/**
 * Copyright 2018 Jonas Blocher
 * <p>
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * <p>
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
 * <p>
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

import org.bukkit.Material;
import org.bukkit.block.Block;
import org.bukkit.block.BlockFace;
import org.bukkit.event.EventHandler;
import org.bukkit.event.EventPriority;
import org.bukkit.event.Listener;
import org.bukkit.event.block.Action;
import org.bukkit.event.block.BlockFromToEvent;
import org.bukkit.event.player.PlayerInteractEvent;

/**
 * Created on 22.04.2018.
 *
 * @author Jonas Blocher
 */
public class ObsidianPreventer implements Listener {

    @EventHandler
    public void onPlaceFluid(PlayerInteractEvent event) {
        if (event.getAction() != Action.RIGHT_CLICK_BLOCK) return;
        Material type;
        if (event.getItem() == null) return;
        if (event.getItem().getType() == Material.WATER_BUCKET) {
            type = Material.WATER;
        } else if (event.getItem().getType() == Material.LAVA_BUCKET) {
            type = Material.LAVA;
        } else return;
        Block block = event.getClickedBlock().getRelative(event.getBlockFace());
        if (generates(type, block)) {
            event.setCancelled(true);
            return;
        } else {
            BlockFace[] nesw = {BlockFace.DOWN, BlockFace.UP, BlockFace.NORTH, BlockFace.EAST, BlockFace.SOUTH, BlockFace.WEST};
            for (BlockFace face : nesw) {
                if (generates(type, block.getRelative(face))) {
                    System.out.println(face);
                    event.setCancelled(true);
                    return;
                }
            }
        }
    }

    @EventHandler(priority = EventPriority.HIGHEST)
    public void disableLavaWaterBlockCreation(BlockFromToEvent event) {
        if (event.isCancelled()) return;
        if (!event.getBlock().isLiquid()) return;
        Material type = event.getBlock().getType();
        Block to = event.getToBlock();
        if (generates(event.getBlock(), to)) {
            event.setCancelled(true);
            return;
        } else {
            BlockFace[] nesw = {BlockFace.DOWN, BlockFace.NORTH, BlockFace.EAST, BlockFace.SOUTH, BlockFace.WEST};
            for (BlockFace face : nesw) {
                if (generates(event.getBlock(), to.getRelative(face))) {
                    event.setCancelled(true);
                    return;
                }
            }
        }

    }

    private boolean generates(Block from, Block to) {
        if (!to.isLiquid()) return false;
        return generates(from.getType(), to.getType());
    }

    private boolean generates(Material from, Block to) {
        if (!to.isLiquid()) return false;
        return generates(from, to.getType());
    }

    private boolean generates(Material from, Material to) {
        if (from == Material.STATIONARY_WATER) from = Material.WATER;
        else if (from == Material.STATIONARY_LAVA) from = Material.LAVA;

        if (to == Material.STATIONARY_WATER) to = Material.WATER;
        else if (to == Material.STATIONARY_LAVA) to = Material.LAVA;

        return from != to;
    }
}

The file was coded to get this working as fast as possible, therfore it's a bit messy. I'm sorry for that.
Maybe at some point I'll rework it and add some comments but for now it just works^^