sk = $sk; $this->date = $date; } public function getSk(): string { return $this->sk; } public function getDate(): ?string { return $this->date; } public static function createFromArray(array $data): self { Assertion::keyExists($data, 'sk', 'The key "sk" is missing'); Assertion::string($data['sk'], 'The key "sk" is invalid'); Assertion::keyExists($data, 'date', 'The key "date" is missing'); Assertion::string($data['date'], 'The key "date" is invalid'); return new self( $data['sk'], $data['date'] ); } public function jsonSerialize(): array { return [ 'sk' => $this->sk, 'date' => $this->date, ]; } }