*<Null safety>*
void encodeMessageWithCallback (Encoder encoder, int inlineSize, dynamic f())
Encodes a FIDL message with multiple parameters. The callback parameter
provides a decoder that is initialized on the provided Message, which
callers can use to decode specific types. This functionality (encoding
multiple parameters) is implemented using a callback because each call to
MemberType.encode() must pass in a concrete type, rather than an element
popped from a List
Implementation
void encodeMessageWithCallback(Encoder encoder, int inlineSize, Function() f) {
encoder.alloc(inlineSize, 0);
f();
}