[Demonstration 1]

[Buggy Method]
private String concating(String... vals) {
    String concat = "";
    if (vals != null) {
        for (String val : vals) {
            if (StringUtils.isNotBlank(val)) {
                concat += (val + ", ");
            }
        }
        concat = concat.substring(0, concat.lastIndexOf(","));
    }
    return concat;
}

[Buggy Hunk]
concat = concat.substring(0, concat.lastIndexOf(","));

[Patch]
if(StringUtils.isNotBlank(concat)) concat = concat.substring(0, concat.lastIndexOf(","));

[Demonstration 2]

[Buggy Method]
public List<UserModel> getUsers() {
    return users;
}

[Buggy Hunk]
public List<UserModel> getUsers() {

[Patch]
public UserModel getUsers() {

[Demonstration 3]

[Buggy Method]
public void parse() {
    logMessage("Begin ");
    try {
        do {
            urlForStart = (findSavedLink() != null) ? findSavedLink() : Parser.BASE;
            Parser.getAllDesigner(urlForStart, Parser.categoryNumb);
            if (countParsedProject == Parser.designers.size()) {
                logMessage("Category ended or poor Internet access");
                break;
            }
            logMessage("End project. Total parsed " + Parser.designers.size() + " links. try to get pictures");
            ArrayList<Designer> authors = Parser.designers;
            String tmp = "";
            if (!lastProjectlink.isEmpty()) {
                for (Designer d : authors) {
                    tmp = (lastProjectlink.trim().equals(d.getName().trim())) ? d.getName() : "";
                    //                                System.out.println(d.getName());
                    if (tmp != "") {
                        iter = authors.indexOf(d);
                        iter++;
                    }
                }
            }
            for (; iter < authors.size(); iter++) {
                Designer d = authors.get(iter);
                if (isInterrupted()) {
                    break;
                }
                makeAll(d);
                Parser.saveLastLink(d);
            }
            countParsedProject = Parser.designers.size();
            if (isInterrupted()) {
                break;
            }
        } while (true);
    } catch (IOException e) {
        logMessage(e.getMessage());
        e.printStackTrace();
    }
    this.main.start.setText("Start");
    this.main.start.setIcon(new ImageIcon(this.getClass().getResource("/kovalenko/elance/aligrabber/resources/tick-button.png")));
    //        this.main.url.setEditable( false );
    this.main.changeTargetDirectory.setEnabled(true);
    this.main.pruneTargetDirectory.setEnabled(true);
    logMessage("End " + iter + " project is parsed.");
}

[Buggy Hunk]
if (isInterrupted()) {

[Patch]
if (isInterrupted() ||  Parser.isFinish) {