Any action or proceeding wherein the validity of the adoption of the retail transactions and use tax ordinance provided for in this article or the issuance of any bonds thereunder or any of the proceedings in relation thereto is contested, questioned, or denied, shall be commenced pursuant to Chapter 9 (commencing with Section 860) of Title 10 of Part 2 of the Code of Civil Procedure. Otherwise, the bonds and all proceedings in relation thereto, including the adoption and approval of the ordinance, shall be held to be valid and in every respect legal and incontestable.
Source:
Section 26293.2, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV§ionNum=26293.2..