KNOW ALL PERSONS BY THESE PRESENTS that STONEBRIDGE 2017, L.P.
(the "Company") does hereby make, constitute and appoint each of
Yvette Kosic, Jamison Yardley, Jennifer Lee and Jess J. Morrison,
acting individually, its true and lawful attorney, to execute and
deliver in its name and on its behalf whether the Company is acting
individually or as representative of others, any and all filings
required to be made by the Company under the Securities Exchange Act
of 1934, (as amended, the "Act"), with respect to securities which
may be deemed to be beneficially owned by the Company under the Act,
giving and granting unto each said attorney-in-fact power and
authority to act in the premises as fully and to all intents and
purposes as the Company might or could do if personally present by
one of its authorized signatories, hereby ratifying and confirming
all that said attorney-in-fact shall lawfully do or cause to be done
by virtue hereof.
THIS POWER OF ATTORNEY shall remain in full force and effect until
the earlier of (i) March 15, 2022 and (ii) such time that it is
revoked in writing by the undersigned; provided that in the event
the attorney-in-fact ceases to be an employee of the Company or its
affiliates or ceases to perform the function in connection with which
he/she was appointed attorney-in-fact prior to such time, this Power
of Attorney shall cease to have effect in relation to such
attorney-in-fact upon such cessation but shall continue in full force
and effect in relation to any remaining attorneys-in-fact. The
Company has the unrestricted right unilaterally to revoke this Power
of Attorney. This Power of Attorney shall be governed by, and
construed in accordance with, the laws of the State of New York,
without regard to rules of conflicts of law.
IN WITNESS WHEREOF, the undersigned has duly subscribed these
presents as of March 15, 2019.
STONEBRIDGE 2017, L.P.
By: Bridge Street Opportunity Advisors, L.L.C.,
its General Partner
/s/ William Y. Eng
Name: William Y. Eng
Title: Attorney-in-Fact