github.com/refraction-networking/utls.UnimplementedECHExtension.mustEmbedUnimplementedECHExtension (method, view implemented interface methods)

one use

	github.com/refraction-networking/utls (current package)
		u_ech.go#L291: func (*UnimplementedECHExtension) mustEmbedUnimplementedECHExtension() {