[Demonstration 1]

[Buggy Method]
private void pickUp(Command command) {
    if (!command.hasSecondWord()) {
        // if there is no second word, we don't know what to pick up...
        System.out.println("Pick up what?");
        return;
    }
    String item = command.getSecondWord();
    if (item.equals("key")) {
        player.sack.add("key");
        currentRoom.giveItem("key");
        System.out.println("You put the key in your sack");
    } else if (item.equals("nuts")) {
        player.sack.add("nuts");
        currentRoom.giveItem("nuts");
        System.out.println("You put the nuts in your sack");
    } else {
        System.out.println("You cannot hold that item");
    }
}

[Buggy Hunk]
if (item.equals("key")){

[Patch]
if (item.equals("key")&&(currentRoom.roomContents.contains("key"))){

[Demonstration 2]

[Buggy Method]
public Command findCommand(String plugin, String command) {
    Map<String, Command> commands = PLUGIN_COMMAND.get(plugin);
    if (commands == null) {
        return null;
    }
    return commands.get(command);
}

[Buggy Hunk]
public Command findCommand(String plugin, String command) {

[Patch]
public synchronized Command findCommand(String plugin, String command) {

[Demonstration 3]

[Buggy Method]
protected static void writeName(String nickname) {
    Font font = new Font("Open Sans", Font.PLAIN, 12);
    JLabel name = new JLabel(nickname.toUpperCase());
    name.setBounds(20, 115, 100, 22);
    name.setFont(font);
    name.setForeground(new Color(255, 255, 255, 255));
    layeredPane.add(name);
    layeredPane.setLayer(name, LAYER_GAME);
    name.setVisible(true);
}

[Buggy Hunk]
JLabel name = new JLabel(nickname.toUpperCase());

[Patch]
JLabel name = new JLabel(nickname);