code: public java.util.List<String> getInvalidUserList() {
          if (invalidUserList == null) {
              invalidUserList = new com.amazonaws.internal.SdkInternalList<String>();
          }
          return invalidUserList;
      }
docs: <p>
  A list of users or groups in the Active Directory that are not allowed to access the file share. A group must be
  prefixed with the @ character. For example <code>@group1</code>. Can only be set if Authentication is set to
  <code>ActiveDirectory</code>.
  </p>
  
  @return A list of users or groups in the Active Directory that are not allowed to access the file share. A group
  must be prefixed with the @ character. For example <code>@group1</code>. Can only be set if
  Authentication is set to <code>ActiveDirectory</code>.