Section 80.00. Bond resolution, or note resolution or certificate, may contain estoppel clause

The resolution of a finance  board  authorizing  the  issuance  of  bonds  or notes, or the certificate of a chief fiscal
  officer authorizing the issuance of notes, may, in the discretion of the
  finance board or such chief fiscal officer, as the case may be,  contain
  a  statement  that  the  validity  of  such  bonds  or notes or any bond
  anticipation notes issued in anticipation of the sale of such bonds  may
  be contested only if:
    1.  Such obligations are authorized for an object or purpose for which
  the  municipality,  school  district  or  district  corporation  is  not
  authorized to expend money, or
    2.  The provisions of law which should be complied with at the date of
  the publication of such resolution or summary thereof,  or  certificate,
  as  the case may be, are not substantially complied with, and an action,
  suit or proceeding contesting such validity, is commenced within  twenty
  days after the date of such publication, or
    3.  Such  obligations are authorized in violation of the provisions of
  the constitution.