The traf box seems to include the sdtp box. valid?

[Kuroishi Mitsuo]

At

mux.js/lib/mp4/mp4-generator.js

Line 631 in 5454bdd

 sampleDependencyTable); 

, the traf box includes the sdtp box doesn't it?

I have the ISO_IEC_14496-12_2015 spec and it doesn't say that the traf can include the sdtp I think.

Is it intensional or valid?