[Demonstration 1]

[Buggy Method]
public static Field getFieldIncludeParents(Class<?> clazz, String name) {
    try {
        Field field = clazz.getField(name);
        field.setAccessible(true);
        return field;
    } catch (NoSuchFieldException ignored) {
        if (clazz.getSuperclass() != null) {
            return getFieldIncludeParents(clazz.getSuperclass(), name);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

[Buggy Hunk]
Field field = clazz.getField(name);

[Patch]
Field field = clazz.getDeclaredField(name);

[Demonstration 2]

[Buggy Method]
public static void main(String[] args) {
    for (String arg : args) if (arg.toLowerCase().startsWith("--runexecutable="))
        runExecutable = arg.toLowerCase().substring(17);
    else if (arg.toLowerCase().startsWith("--compileexecutable="))
        compileExecutable = arg.toLowerCase().substring(20);
    try {
        //GTK doesn't always want to show up.
        UIManager.setLookAndFeel(com.sun.java.swing.plaf.gtk.GTKLookAndFeel.class.getName());
    } catch (IllegalAccessException | InstantiationException | UnsupportedLookAndFeelException | ClassNotFoundException | NoClassDefFoundError _e) {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (IllegalAccessException | InstantiationException | UnsupportedLookAndFeelException | ClassNotFoundException | NoClassDefFoundError e) {
            JFrame frame = new JFrame();
            JOptionPane.showMessageDialog(frame, "Initialization error", e.getMessage(), JOptionPane.ERROR_MESSAGE);
            frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
            return;
        }
    }
    EventQueue.invokeLater(() -> (new G_Lite()).setVisible(true));
}

[Buggy Hunk]
UIManager.setLookAndFeel(com.sun.java.swing.plaf.gtk.GTKLookAndFeel.class.getName());

[Patch]
UIManager.setLookAndFeel(GTKLookAndFeel.class.getName());

[Demonstration 3]

[Buggy Method]
@Override
public void set(int i, int j, float x) {
    if (i < 0 || i >= nrow || j < 0 || j >= ncol)
        throw new IllegalArgumentException();
    Entry e = new Entry(i, j);
    if (x == 0) {
        if (nonZero.containsKey(e)) {
            nonZero.remove(e);
            nonZeroPerRow.get(j).remove(e);
        }
    } else {
        nonZero.put(e, x);
        if (!nonZeroPerRow.containsKey(i))
            nonZeroPerRow.put(i, new HashMap<Entry, Float>(ncol));
        nonZeroPerRow.get(i).put(e, x);
    }
}

[Buggy Hunk]
nonZeroPerRow.get(j).remove(e);

[Patch]
nonZeroPerRow.get(i).remove(e);