We're going to allow the provider to encode whatever it wants in here, so
a provider can use whatever is most convenient for its implementation
language and to avoid some of the bugs we saw with the prior model where
the forced round-trip through JSON and back into interface{} would cause
some loss of fidelity, leading to bugs.
The types here were originally written to allow us to defer decoding of
object values until schemas are available, but it turns out that this was
forcing us to defer decoding longer than necessary and potentially decode
the same value multiple times.
To avoid this, we create pairs of types to represent the encoded and
decoded versions and methods for moving between them. These types are
identical to one another apart from how the dynamic values are
represented.
Martin Atkins