Interface that defines implementation for selectors assigned to a ResourcePool. ResourcePoolSelector helps to
evaluate if a given query can be admitted into a ResourcePool or not. Based on the assigned selector type to a
ResourcePool it uses the query metadata with it's own configured values and make a decision for a query. The
SelectorType defines all the supported ResourcePoolSelector which can be assigned to a ResourcePool. The
configuration of a selector is of type:
selector: {
SelectorType:SelectorValue
}
where SelectorValue can be a string (for SelectorType tag),
object (for SelectorType acl and not_equal) and
list of objects (for SelectorType and, or)
when selector config is absent then a DefaultSelector is associated with the ResourcePool