private function createData() : void
    {
        $this->data = [
            'foo' => 'some foo string',
            'bar' => 42,
            'baz' => new DateTime(),
            'someFooProperty' => [12, 13, 14],
            'someBarProperty' => 12354.4578,
            'someBazProperty' => new stdClass(),
            'foo1' => 'some foo string',
            'bar1' => 42,
            'baz1' => new DateTime(),
            'someFooProperty1' => [12, 13, 14],
            'someBarProperty1' => 12354.4578,
            'someBazProperty1' => new stdClass(),
            'foo2' => 'some foo string',
            'bar2' => 42,
            'baz2' => new DateTime(),
            'someFooProperty2' => [12, 13, 14],
            'someBarProperty2' => 12354.4578,
            'someBazProperty2' => new stdClass(),
        ];
    }