Lisner
------
package cog.stem;

import java.util.Random;
import org.bukkit.Material;
import org.bukkit.Server;
import org.bukkit.block.Block;
import org.bukkit.block.BlockFace;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.block.BlockFromToEvent;
import org.bukkit.plugin.PluginManager;

public class ListenerClass implements Listener
{
    private static Random r = new Random();

    public ListenerClass(COG plugin) {
        plugin.getServer().getPluginManager().registerEvents(this, plugin);
    }

    @EventHandler
    public void onFromTo(BlockFromToEvent e)
    {
        int id = e.getBlock().getTypeId(Material.AIR);
        if ((id >= 8) && (id <= 11)) {
            Block b = e.getToBlock();
            int toid = b.getTypeId();
            if ((toid == 0) &&
                    (generatesCobble(id, b))) {
                for (BlockFace face : facesCobble) {
                    Block r = e.getBlock().getRelative(face, 1);
                    if (r.getTypeId() == 0) {
                        for (BlockFace face2 : faces) {
                            int mirrorID1 = (id == 8) || (id == 9) ? 10 : 8;
                            int mirrorID2 = (id == 8) || (id == 9) ? 11 : 9;
                            Block o = r.getRelative(face2, 1);
                            if ((o.getTypeId() == mirrorID1) || (o.getTypeId() == mirrorID2)) {
                                int i = 1;
                                while (i == 1) {
                                    if (r.nextInt(100) <= CobbleOres.Cobblestone) {
                                        r.setType(Material.COBBLESTONE);
                                        i = 0;
                                    } else if (r.nextInt(100) <= CobbleOres.Coal) {
                                        r.setType(Material.COAL_ORE);
                                        i = 0;
                                    } else if (r.nextInt(100) <= CobbleOres.Iron) {
                                        r.setType(Material.IRON_ORE);
                                        i = 0;
                                    } else if (r.nextInt(100) <= CobbleOres.Lapis) {
                                        r.setType(Material.LAPIS_ORE);
                                        i = 0;
                                    } else if (r.nextInt(100) <= CobbleOres.Redstone) {
                                        r.setType(Material.REDSTONE_ORE);
                                        i = 0;
                                    } else if (r.nextInt(100) <= CobbleOres.Gold) {
                                        r.setType(Material.GOLD_ORE);
                                        i = 0;
                                    } else if (r.nextInt(100) <= CobbleOres.Diamond) {
                                        r.setType(Material.DIAMOND_ORE);
                                        i = 0;
                                    } else if (r.nextInt(100) <= CobbleOres.Emerald) {
                                        r.setType(Material.EMERALD_ORE);
                                        i = 0;
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }

    private final BlockFace[] faces = {
            BlockFace.SELF,
            BlockFace.UP,
            BlockFace.DOWN,
            BlockFace.NORTH,
            BlockFace.EAST,
            BlockFace.SOUTH,
            BlockFace.WEST };


    private final BlockFace[] facesCobble = {
            BlockFace.NORTH,
            BlockFace.EAST,
            BlockFace.SOUTH,
            BlockFace.WEST };


    public boolean generatesCobble(int id, Block b)
    {
        int mirrorID1 = (id == 8) || (id == 9) ? 10 : 8;
        int mirrorID2 = (id == 8) || (id == 9) ? 11 : 9;
        for (BlockFace face : faces) {
            Block r = b.getRelative(face, 1);
            if ((r.getTypeId() == mirrorID1) || (r.getTypeId() == mirrorID2)) {
                return true;
            }
        }
        return false;
    }
}


COG
----
package cog.stem;

import org.bukkit.configuration.file.FileConfiguration;

public class COG extends org.bukkit.plugin.java.JavaPlugin
{
    public COG() {}

    public static String prefix = net.md_5.bungee.api.ChatColor.GRAY + "[" + net.md_5.bungee.api.ChatColor.DARK_GRAY + "CobbleOres" + net.md_5.bungee.api.ChatColor.GRAY + "] " + net.md_5.bungee.api.ChatColor.WHITE;

    public static int Cobblestone = 45;
    public static int Coal = 35;
    public static int Iron = 25;
    public static int Lapis = 15;
    public static int Redstone = 15;
    public static int Gold = 10;
    public static int Diamond = 5;
    public static int Emerald = 1;

    public void onEnable() {
        new ListenerClass(this);
        if (getConfig().getString("Dont Remove") != null) {
            Cobblestone = getConfig().getInt("Cobblestone");
            Coal = getConfig().getInt("Coal");
            Iron = getConfig().getInt("Iron");
            Lapis = getConfig().getInt("Lapis");
            Redstone = getConfig().getInt("Redstone");
            Gold = getConfig().getInt("Gold");
            Diamond = getConfig().getInt("Diamond");
            Emerald = getConfig().getInt("Emerald");
        } else {
            getConfig().set("Cobblestone", Integer.valueOf(Cobblestone));
            getConfig().set("Coal", Integer.valueOf(Coal));
            getConfig().set("Iron", Integer.valueOf(Iron));
            getConfig().set("Lapis", Integer.valueOf(Lapis));
            getConfig().set("Redstone", Integer.valueOf(Redstone));
            getConfig().set("Gold", Integer.valueOf(Gold));
            getConfig().set("Diamond", Integer.valueOf(Diamond));
            getConfig().set("Emerald", Integer.valueOf(Emerald));
        }
        getConfig().set("Dont Remove", "Or Config Will Reset Also Don't Put Numbers Over 100");
        saveConfig();
    }
}