Base URL of the witness backend whose raw block built the reveal's
witness section, when one was attached. The section loop asks the
members directly rather than through the pool, so the server is not in
usedBaseUrls; a caller assembling header trust adds it to
proofSources by name, the way custodybuilder does, because a server
vouching for a header it helped build is a self-vote whichever bytes it
contributed.
Base URL of the witness backend whose raw block built the reveal's witness section, when one was attached. The section loop asks the members directly rather than through the pool, so the server is not in
usedBaseUrls; a caller assembling header trust adds it toproofSourcesby name, the waycustodybuilderdoes, because a server vouching for a header it helped build is a self-vote whichever bytes it contributed.