TypeUrl: A URL/resource name whose content describes the type of the serialized protocol buffer message.
For URLs which use the scheme `http`, `https`, or no scheme, the following restrictions and interpretations apply:
* If no scheme is provided, `https` is assumed. * The last segment of the URL's path must represent the fully qualified name of the type (as in `path/google.protobuf.Duration`). The name should be in a canonical form (e.g., leading "." is not accepted). * An HTTP GET on the URL must yield a [google.protobuf.Type] value in binary format, or produce an error. * Applications are allowed to cache lookup results based on the URL, or have them precompiled into a binary to avoid any lookup. Therefore, binary compatibility needs to be preserved on changes to types. (Use versioned type names to manage breaking changes.)
Schemes other than `http`, `https` (or the empty scheme) might be used with implementation specific semantics.