Change A Players Skin

I'm trying to use the Mojang API to create a command that would change your skin to another player's skin. I'm using the command /skin <PlayerName> and then I'm turning the name into a UUID with the Mojang API. Finally I'm replacing the texture of the sender using his game profile. I've got no errors at all but the only feedback I get in game it's an actual repeat of the command (So basically the command usage that I specified in the plugin.yml)

That's my code

Code:

public class SkinChanger extends JavaPlugin implements CommandExecutor {

    private UUID targetId;
    private String textureID;
    private String Signature;

    @Override
    public void onEnable() {

        System.out.println(ChatColor.GREEN + "Skin changer enabled!");
    }

    public UUID fromTrimmed(String trimmedUUID) throws IllegalArgumentException{
        if(trimmedUUID == null) throw new IllegalArgumentException();
        StringBuilder builder = new StringBuilder(trimmedUUID.trim());
        /* Backwards adding to avoid index adjustments */
        try {
            builder.insert(20, "-");
            builder.insert(16, "-");
            builder.insert(12, "-");
            builder.insert(8, "-");
        } catch (StringIndexOutOfBoundsException e){
            throw new IllegalArgumentException();
        }

        return UUID.fromString(builder.toString());
    }


    public void ChangeSkin(GameProfile profile) {

        String url = "https://sessionserver.mojang.com/session/minecraft/profile/" + targetId.toString();

        try {
            URL site = new URL(url);

            HttpURLConnection connection = (HttpURLConnection) site.openConnection();

            connection.setRequestMethod("GET");

            connection.connect();

            InputStream input = connection.getInputStream();

            BufferedReader reader = new BufferedReader(new InputStreamReader(input, StandardCharsets.UTF_8));

            StringBuffer buffer = new StringBuffer();

            String line;

            while ((line = reader.readLine()) != null) {

                buffer.append(line.trim());

            }

            reader.close();
            connection.disconnect();

            String result = buffer.toString();

            JsonObject object = (JsonObject)(new Gson()).fromJson(result, JsonObject.class);

            JsonArray array = object.getAsJsonArray("properties");

            textureID = new String(array.get(0).getAsJsonObject().get("value").getAsString());


        } catch (IOException ex) {
            ex.printStackTrace();
        }

        profile.getProperties().put("textures", new Property("textures", textureID));

    }

    @Override
    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {

        if (cmd.getName().equalsIgnoreCase("skin")) {

            if (!(sender instanceof Player)) {
                sender.sendMessage(ChatColor.RED + "Do you really think that the console can change it's skin?");

                return true;
            }

            Player p = (Player) sender;

            if (args.length == 0) {
                sender.sendMessage(ChatColor.RED + "Please specify the name of the player whose skin you'd like to put on!");

                return true;
            }



            try {

                URL site = new URL("https://api.mojang.com/users/profiles/minecraft/" + args[0]);

                HttpURLConnection connection = (HttpURLConnection) site.openConnection();

                connection.setRequestMethod("GET");

                connection.connect();

                InputStream input = connection.getInputStream();

                BufferedReader reader = new BufferedReader(new InputStreamReader(input, StandardCharsets.UTF_8));

                StringBuffer buffer = new StringBuffer();

                String line;

                while ((line = reader.readLine()) != null) {

                    buffer.append(line.trim());

                }

                reader.close();
                connection.disconnect();

                String result = buffer.toString();

                JsonObject object = (JsonObject)(new Gson()).fromJson(result, JsonObject.class);

                targetId = fromTrimmed(object.get("id").getAsString());
            } catch (IOException ex) {
                sender.sendMessage(ChatColor.RED + "An internal error occurred and we couldn't change your skin!");

                return true;
            }


            try {
                ChangeSkin(new GameProfile(p.getUniqueId(), p.getName()));
            } catch (Exception ex) {
                ex.printStackTrace();
                return true;
            }
        } else {
            return true;
        }

        return false;
    }
}

Any help???