* Fills given user instance with all available data
* <p>
* @param user Initial User instance
+ * <p>
* @return Prepared User instance
*/
public User fillUserData (final User user);
* Checks if the the given user's name is already registered
* <p>
* @param user User instance
+ * <p>
* @return Whether the user is already registered
*/
public boolean isUserNameReqistered (final User user);
* Checks if the the given user's email address is already registered
* <p>
* @param user User instance
+ * <p>
* @return Whether the user is already registered
*/
public boolean isEmailAddressReqistered (final User user);