Fix builder.Intervals marshal and filter.Interval

[cosmic-chichu]

Currently, builder.Intervals supports only complex interval types during Load. But when marshaled it produces a simple interval. This behavior violates the expected idempotent behavior of marshaling and un-marshaling.

Steps to reproduce:

interval := NewInterval().SetInterval(start,end)
intervals := NewIntervals().SetIntervals([]*Interval{interval})
f, err := json.Marshal(interval)
fmt.Println(string(f))

Actual Output: ["2022-06-16T08:28:53.33441Z/2022-06-16T15:28:53.33441Z"]
Expected Output: {"type":"intervals","intervals":["2022-06-16T08:28:53.33441Z/2022-06-16T15:28:53.33441Z"]}

Note: This change ensures the intervals are always processed(input/output) as a well-defined struct.

This also relates to #17 and #18 and provides a fix

Filters have a different struct defined for interval which only requires intervals of type []*intervals.Interval.

[cosmic-chichu]

@jbguerraz @vigith Load intervals was not compliant to the full spec causing problems in chaining go-druid clients.
Scenario:
A - web application
P - Proxy
D - Druid

A (go-druid builder query marshaled ) -> Proxy (tries to load json but fails) -> Druid.

Please don't mind the older commits, I lost my local copy. We can squash these.

[vigith]

does this fix #18 ?

[cosmic-chichu]

does this fix #18 ?

Thank you for the pointer! I fixed the filter's Interval type. It only cares about the interval of type []*intervals.Interval from builder.Intervals. The type is explicitly/statically set here

I verified the query output with multiple filters works:

"queryType":"scan","dataSource":{"type":"table","name":"wikipedia"},"intervals":{"type":"intervals","intervals":["2022-06-16T08:28:53.33441Z/2022-06-16T15:28:53.33441Z"]},"limit":10,"filter":{"type":"or","fields":[{"type":"selector","dimension":"countryName","value":"France"},{"type":"interval","dimension":"__time","intervals":["2022-06-16T08:28:53.33441Z/2022-06-16T15:28:53.33441Z","2022-06-12T08:28:53.33441Z/2022-06-12T15:28:53.33441Z"]}]}}

[vigith]

can you add a test where we marshal, unmarshal and then marshal and make sure it matches the input we started with?

[jbguerraz]

thank you @cosmic-chichu !!! 🎆