simple static method
Implementation
static AuthMetadata simple(String username, String password) {
var userNameU8Array = utf8.encode(username);
var passwordU8Array = utf8.encode(password);
var buffer = RSocketByteBuffer();
buffer.writeI24(userNameU8Array.length);
buffer.writeBytes(userNameU8Array);
buffer.writeBytes(passwordU8Array);
return AuthMetadata(0x00, buffer.toUint8Array());
}