Consider additional java classes for whitelisting

[geekpete]

Consider the following classes for whitelisting:

• org.elasticsearch.common.unit.DistanceUnit
• org.elasticsearch.common.geo.GeoUtils
• org.elasticsearch.common.geo.GeoDistance

For the purposes of performing unit conversions when doing arc distance calculations.
Alternatively provide functions in Painless that wrap necessary classes to perform the same unit conversions and calculations.

These examples (though these are groovy examples rather than painless ones, the use case is still valid). These examples require whitelisting of the classes involved.

Using DistanceUnit and GeoUtils classes:

GET /test/type/_search
{
    "script_fields" : {
        "test1" : {
            "script" : {
                "lang": "groovy",
                "inline": "org.elasticsearch.common.unit.DistanceUnit.MILES.fromMeters(org.elasticsearch.common.geo.GeoUtils.arcDistance(0.0, 0.0, 1.0, 1.0))"
            }
        }
    }
}

alternatively using GeoDistance and DistanceUnit classes:

_source['NETWORK_LOCATION'].collectEntries { it -> if (it != null && it.COORDINATES != null){ [(it.PCO_NET_LOC_CYCLE_CK.toString()) : org.elasticsearch.common.geo.GeoDistance.ARC.calculate(it.COORDINATES.lat, it.COORDINATES.lon, lat, lon, org.elasticsearch.common.unit.DistanceUnit.MILES)]} else{[('-1'):'-1']}} 

[geekpete]

Possibly related: #17506

[jdconrad]

Adding discuss to talk about which contexts make sense to have these new APIs. Really falls under context/whitelist clean up.

[jdconrad]

Given the speed at which the contexts are being developed it probably makes sense to add these to the default whitelist for now and move them to the appropriate contexts when they're ready.