getHeaderPlain example

$this->repository->create(array_values($data), $this->context);

        foreach ($data as $expect) {
            $id = $expect['id'];
            $mailHeaderFooter = $this->repository->search(new Criteria([$id]), $this->context)->get($id);
            static::assertInstanceOf(MailHeaderFooterEntity::class, $mailHeaderFooter);
            static::assertEquals($expect['systemDefault'], $mailHeaderFooter->getSystemDefault());
            static::assertEquals($expect['name'], $mailHeaderFooter->getName());
            static::assertEquals($expect['description'], $mailHeaderFooter->getDescription());
            static::assertEquals($expect['headerHtml'], $mailHeaderFooter->getHeaderHtml());
            static::assertEquals($expect['headerPlain'], $mailHeaderFooter->getHeaderPlain());
            static::assertEquals($expect['footerHtml'], $mailHeaderFooter->getFooterHtml());
            static::assertEquals($expect['footerPlain'], $mailHeaderFooter->getFooterPlain());
        }
    }

    /** * Test UPDATE */
    public function testMailHeaderFooterUpdate(): void
    {
        $num = 10;