Cannot request events delta without startDateTime

Describe the bug

Event delta documentation says param startDateTime is optional when working with calendars but class DeltaRequestBuilder always include it in template url causing call to fail with ODataError.

Expected behavior

When performing a normal call without any optional param to get a full delta, no error should append.

How to reproduce

$client->me()
->calendars()
->byCalendarId($remoteId)
->events()
->delta()
->get(
    new DeltaRequestBuilderGetRequestConfiguration([
        'Prefer' => sprintf('outlook.timezone="%s"', $local->getTimeZone()->getName())
    ])
)
->wait()

SDK Version

2.8.0

Latest version known to work for scenario above?

No response

Known Workarounds

No response

Debug output

{
    "error": {
        "code": "ErrorInvalidParameter",
        "message": "The value '' of parameter 'StartDateTime' is invalid."
    }
}

Configuration

No response

Other information

No response

从 src/Generated/Users/Item/Calendars/Item/Events/Delta/DeltaRequestBuilder.php 开始，将其模板 URL 与 issue 中链接的 Event delta 文档进行比较。在不提供 startDateTime 的情况下复现日历 delta 请求；当请求能够成功执行且不出现无效的 StartDateTime 错误，同时提供该参数的请求仍然正常工作时，即表示完成。