SegmentMetadata request without Interval includes empty Interval by default

[TomBonnerAtDerivitec]

Hihi

When making a SegmentMetadata request without a Interval call (which is optional to Druid) it includes "intervals":[] in the resulting call to Druid which invalidates the result.

It's an easy work-around to pass DateTime.Min and DateTime.Max, but thought I'd highlight this here. I'll try put a PR together to fix it.

[QuantumNightmare]

Thanks for pointing this out, a PR would be much appreciated.