LPS-50830 1st step - fix isssue: Can not get String array from Expandovalue with "Group of Text Values" in case of Custom Fields for DM
LPS-50830 2nd step: change methods getExpandoBridgeAttributes and getExpandoValue to reduce code duplication: UploadPortletReqest extends HttpServletRequest so it doesn't break anything
LPS-50830 keep the old APIs for backward compatibility