OptionalresolversA store that, given a common URI, returns the corresponding MediaBlob. The returned MediaBlob may have a different URI. In many cases, this will be a ReadThroughStore or something similar that has a cached version of the MediaBlob, but also a way to get a new (or refreshed) version.
BlobStores that can resolve a URL into the MediaBlob to save in the canonical store. This list is evaluated in order. If not provided, a default list (which involves a DataBlobStore and a SimpleWebBlobStore) will be used.