docs: private String getQualifiedMailboxName(GreenMailUser user, String mailboxName) {
          String userNamespace = user.getQualifiedMailboxName();
  
          if ("INBOX".equalsIgnoreCase(mailboxName)) {
              return USER_NAMESPACE + HIERARCHY_DELIMITER + userNamespace +
                      HIERARCHY_DELIMITER + INBOX_NAME;
          }
  
          if (mailboxName.startsWith(NAMESPACE_PREFIX)) {
              return mailboxName;
          } else {
              if (mailboxName.length() == 0) {
                  return USER_NAMESPACE + HIERARCHY_DELIMITER + userNamespace;
              } else {
                  return USER_NAMESPACE + HIERARCHY_DELIMITER + userNamespace +
                          HIERARCHY_DELIMITER + mailboxName;
              }
          }
      }