#vulnerable code 
                              public void hasField(String fieldName) {
    if (getSubject() == null) {
      failWithoutSubject("<null> has a field named <" + fieldName + ">");
    }
    Class<?> clazz = getSubject().getClass();
    try {
      clazz.getField(fieldName);
    } catch (NoSuchFieldException e) {
      StringBuilder message = new StringBuilder("Not true that ");
      message.append("<").append(getSubject().getClass().getSimpleName()).append(">");
      message.append(" has a field named <").append(fieldName).append(">");
      failureStrategy.fail(message.toString());
    }
  } 
                            #location 5 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              public void hasField(String fieldName) {
    if (getSubject() == null) {
      failureStrategy.fail("Cannot determine a field name from a null object.");
      return; // not all failures throw exceptions.
    }
    check().that(getSubject().getClass()).hasField(fieldName);
  }