How to copy chunks in api version 1.14

I am trying to copy chunks from one world to another, however when I try it is copying one slice and then pasting it to fill the rest of the chunk. Here is my methood.

Code:

public static void copyChunk(Chunk from, Chunk to) {
        Block fromBlock;
        Block toBlock;
        Block[][][] xyz = new Block[16][16][256];
        for (int x = 0; x < 16; x++) {
            for (int y = 0; y < 256; y++) {
                for (int z = 0; z < 16; z++) {
                    xyz[x][y][z] = from.getBlock(x, y, z);
                }
            }
        }
        for (int i = 0; i < xyz.length; i++) {
            for (int j = 0; j < xyz[i].length; j++) {
                for (int k = 0; k < xyz[j].length; k++) {
                    int x = i;
                    int z = j;
                    int y = k;
                    fromBlock = from.getBlock(x, y, z);
                    toBlock = to.getBlock(x, y, z);
                    toBlock.setType(fromBlock.getType());
                    toBlock.getState().setType(toBlock.getState().getType());
                    toBlock.getState().setData(fromBlock.getState().getData().clone());
                    toBlock.getState().update();
                }
            }
        }
    }

 

It seems like the code stops at the for loops this code does not run.

Code:

        Block fromBlock;
        Block toBlock;
        Block[][][] xyz = new Block[16][16][256];
        p.sendMessage(":(");
        for (int x = 0; x < 16; x++) {
            p.sendMessage(":(x");
            for (int y = 0; y < 256; y++) {
                p.sendMessage(":(xy");
                for (int z = 0; z < 16; z++) {
                    p.sendMessage(":(xyz");
                    xyz[x][y][z] = from.getBlock(x, y, z);
                    p.sendMessage(":((((((((");
                }
            }
        }
      
        for (int x = 0; x < xyz.length; x++) {
            for (int y = 0; y < xyz[x].length; y++) {
                for (int z = 0; z < xyz[x][y].length; z++) {
                    p.sendMessage(Integer.toString(x) + " " + Integer.toString(y) + " " + Integer.toString(z));
                    fromBlock = from.getBlock(x, y, z);
                    toBlock = to.getBlock(x, y, z);
                    toBlock.setType(fromBlock.getType());
                    toBlock.getState().setType(toBlock.getState().getType());
                    toBlock.getState().setData(fromBlock.getState().getData().clone());
                    toBlock.getState().update();
                }
            }
        }
    }

I am not getting any of the p.sendMessage commands that are inside the for loops