Written objection to the proposed changes may be filed with the clerk of the legislative body by any interested person at any time not later than the time set for the hearing. The legislative body shall hear and pass upon such objections at the time appointed, or at any time to which the hearing thereof may be adjourned, and its decision thereon shall be final and conclusive. If no written objections to said changes have been delivered to the clerk up to the hour set for hearing thereon, or if said objections have been heard and found by the legislative body to be insufficient or have been overruled or denied, immediately thereupon the legislative body by an affirmative vote of four-fifths of its members shall acquire jurisdiction to order said changes made. The decisions and determinations of the legislative body ordering such changes after notice and hearing shall be final and conclusive upon all persons entitled to appeal thereupon to the legislative body.