An ObjectType represents the type of an object in a query.
An ObjectType is similar to a Class, except unlike a Class it can be
extended to add more information such as a subtype for collection Classes,
a key type for a map class, or a field information for structs.
Note that multiple instances of are allowed of the same type, so ObjectTypes
should always be compared using equals.
Return true if this is a CollectionType. Note that MapTypes, Region types,
and array types are also considered CollectionTypes in the context of the
query language and therefore return true to this method.