How to convert LocalDateTime to GregorianCalendar?
<p>Why is it possible to pass a <code>LocalDateTime</code> object into the <code>ZonedDateTime.from()</code> method, if it's not possible to parse a simple <code>DateTime</code>, as follows?</p>

<pre><code>@Test
public void test() throws Exception {
    GregorianCalendar.from(ZonedDateTime.from(LocalDateTime.parse("2016-08-31T23:00:59")));
}
</code></pre>

<p>Result:</p>

<pre><code>java.time.DateTimeException: Unable to obtain ZonedDateTime from TemporalAccessor: 2016-08-31T23:00:59 of type java.time.LocalDateTime
    at java.time.ZonedDateTime.from(ZonedDateTime.java:565)
</code></pre>