Adds candidate endpoints to the list of endpoints to
        attempt to peer with.

        Args:
            peer_endpoints ([str]): A list of public uri's which the
                validator can attempt to peer with.

def add_candidate_peer_endpoints(self, peer_endpoints):
        """Adds candidate endpoints to the list of endpoints to
        attempt to peer with.

        Args:
            peer_endpoints ([str]): A list of public uri's which the
                validator can attempt to peer with.
        """
        with self._lock:
            for endpoint in peer_endpoints:
                if endpoint not in self._candidate_peer_endpoints:
                    self._candidate_peer_endpoints.append(endpoint)