Code of Civil Procedure § 869

869.

No contest except by the public agency or its officer or agent of any thing or matter under this chapter shall be made other than within the time and the manner herein specified. The availability to any public agency, including any local agency, or to its officers or agents, of the remedy provided by this chapter, shall not be construed to preclude the use by such public agency or its officers or agents, of mandamus or any other remedy to determine the validity of any thing or matter.