Description:
------------
According the documentation the methods DateTime::setTime and DateTimeImmutable::setTime have 3 parameters, but by using reflection we can see there is a 4th parameter ("microseconds").

http://php.net/manual/en/datetime.settime.php
http://php.net/manual/en/datetimeimmutable.settime.php

Test script:
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<?php

$rm = new ReflectionMethod(DateTime::class, "setTime");
printf("%d\n%d\n", $rm->getNumberOfParameters(), $rm->getNumberOfRequiredParameters());
foreach ($rm->getParameters() as $param) {
    printf("Parameter #%d (%s) %s OPTIONAL\n", $param->getPosition(), $param->getName(), $param->isOptional() ? "IS" : "IS NOT");
}

Actual result:
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4
2
Parameter #0 (hour) IS NOT OPTIONAL
Parameter #1 (minute) IS NOT OPTIONAL
Parameter #2 (second) IS OPTIONAL
Parameter #3 (microseconds) IS OPTIONAL