Section 15. Any holder of bonds or debentures issued under the provisions of this chapter or of any coupons appertaining thereto, and the trustee, except to the extent the rights herein given may be restricted by the trust agreement, may, either at law or in equity, by suit, action, mandamus or other proceeding, protect and enforce any and all rights under the laws of the commonwealth or granted hereunder or under the trust agreement, and may enforce and compel the performance of all duties required by this act or by the trust agreement, to be performed by the corporation or by any officer thereof.