Checks if this trait is persisted with the shape, or if it is a synthetic,
or transient trait, only meant to temporarily aid in some kind of
in-memory model transformation.
If set to true, indicates that this protocol does not support document
type shapes. A service that uses such a protocol MUST NOT contain any
document shapes in their service closure.
List of shape IDs that protocol implementations MUST understand in order
to successfully use the protocol. Each shape MUST exist and MUST be a
trait. Code generators SHOULD ensure that they support each listed trait.