Bonds; qualities of negotiable instruments; rights of holders.

All revenue bonds, general obligation bonds or assessment bonds issued hereunder shall be and constitute, and have all the qualities and incidents of negotiable instruments under the law merchant and the negotiable instruments law of Florida, and shall not be invalid for any irregularity or defect in the proceedings for the issuance and sale thereof and shall be incontestable in the hands of bona fide purchasers for value. No proceedings in respect to the issuance of such bonds shall be necessary except such as are required by this law. The provisions of this law shall constitute an irrevocable contract between said district and the holders of any such bonds or coupons thereof issued pursuant to the provisions hereof. Any holder of such bonds may either at law or in equity, by suit, action or mandamus, enforce and compel the performance of the duties required by this law or of any of the officers or persons herein mentioned in relation to said bonds, or the levy, assessment, collection and enforcement and application of the taxes, revenues, assessments or other funds pledged for the payment of the principal and interest thereof.