get the mailnickname value . concode_field_sep String mail concode_elem_sep String displayName concode_elem_sep String signInName concode_elem_sep String objectId concode_elem_sep String userPrincipalName concode_elem_sep String objectType concode_elem_sep String mailNickname concode_field_sep UserInner withUserPrincipalName concode_elem_sep String mail concode_elem_sep String displayName concode_elem_sep UserInner withMailNickname concode_elem_sep String objectType concode_elem_sep UserInner withDisplayName concode_elem_sep UserInner withObjectId concode_elem_sep String signInName concode_elem_sep UserInner withMail concode_elem_sep UserInner withObjectType concode_elem_sep UserInner withSignInName concode_elem_sep String objectId concode_elem_sep String userPrincipalName
String function ( ) { return this . mailNickname ; }