Apparently Adam has pledged $1B in charitable donations over the next 10 years, otherwise he loses voting power. Is this normal?

>To evidence their commitment to charitable causes and to ensure this commitment is meaningful, if Adam and Rebekah have not contributed at least $1 billion to charitable causes as of the ten-year anniversary of the closing date of this offering, holders of all of the Company's high-vote stock will only be entitled to ten votes per share instead of twenty votes per share.```