Options for the 'memory' arm — a real single-process transport, not a
no-op. Instances sharing one process see each other; separate processes do
not.
optional
transport: "memory"
Transport discriminant.
readonly
optional
bus: string
The name of the process-wide bus this instance joins. Two backplanes built
with the same name exchange frames; different names are isolated, which is
what keeps concurrent tests from bleeding into each other.
Defaults to 'default'.