code: public char[] passwordHash(char[] password) {
          if (null == password) {
              return null;
          }
          return BCrypt.hashpw(password, BCrypt.gensalt());
      }
docs: Generate crypted hash of given password. This method is more secure than
  {@link #passwordHash(String)} as it will fill the password char array
  with `\0` once used.
  
  See <a href="http://stackoverflow.com/questions/8881291/why-is-char-preferred-over-string-for-passwords-in-java">This SO for more detail</a>
  @param password the password
  @return the password hash