[Demonstration 1]

[Buggy Method]
@Test
public void testDeleteUser() {
    // DeleteUser@javamonkeys.com / 12345 / in Base64
    String basicAuth = "Basic RGVsZXRlVXNlckBqYXZhbW9ua2V5cy5jb206MTIzNDU=";
    RestTemplate restTemplate = new RestTemplate();
    restTemplate.setErrorHandler(customResponseErrorHandler);
    // LOGIN for check user id
    HttpHeaders headers = new HttpHeaders();
    headers.add("Authorization", basicAuth);
    HttpEntity<String> entity = new HttpEntity<String>(headers);
    ResponseEntity<User> responseEntityUser = restTemplate.exchange(baseUrl + "/api/users/login", HttpMethod.GET, entity, User.class);
    User currentUser = responseEntityUser.getBody();
    // DELETE user
    headers = new HttpHeaders();
    entity = new HttpEntity<String>(headers);
    ResponseEntity responseEntity = restTemplate.exchange(baseUrl + "/api/users/" + currentUser.getId(), HttpMethod.DELETE, entity, String.class);
    assertEquals(HttpStatus.NO_CONTENT, responseEntity.getStatusCode());
    assertNull(responseEntity.getBody());
    // Check user
    headers = new HttpHeaders();
    entity = new HttpEntity<String>(headers);
    responseEntityUser = restTemplate.exchange(baseUrl + "/api/users/" + currentUser.getId(), HttpMethod.GET, entity, User.class);
    assertEquals(HttpStatus.OK, responseEntityUser.getStatusCode());
    assertNull(responseEntity.getBody());
    // Incorrect user id
    headers = new HttpHeaders();
    entity = new HttpEntity<String>(headers);
    responseEntity = restTemplate.exchange(baseUrl + "/api/users/-999", HttpMethod.DELETE, entity, String.class);
    assertEquals(HttpStatus.NOT_FOUND, responseEntity.getStatusCode());
    assertNull(responseEntity.getBody());
}

[Buggy Hunk]
assertNull(responseEntity.getBody());

[Patch]
assertNull(responseEntityUser.getBody());

[Demonstration 2]

[Buggy Method]
protected MultiValueMap getHeaders() {
    MultiValueMap headers = new HttpHeaders();
    headers.put("Cookie", Arrays.asList(new String[] { getCookies() }));
    return headers;
}

[Buggy Hunk]
headers.put("Cookie", Arrays.asList(new String[]{getCookies()}));

[Patch]
headers.put("Cookie", Arrays.asList(new String[]{getCookiesString()}));

[Demonstration 3]

[Buggy Method]
public static void main(String[] args) {
    final int[] INDEX_ARRAY = { 0, 1, 2, 3, 4, 6 };
    int[] values = { 0, 1, 2, 3, 4 };
    for (int i = 0; i < INDEX_ARRAY.length; i++) {
        values[INDEX_ARRAY[i]] = i;
    }
}

[Buggy Hunk]
final int [] INDEX_ARRAY = {0,1,2,3,4,6};

[Patch]
final int [] INDEX_ARRAY = {0,1,2,3,4};