Given this structure:
Outer = OUTER-TYPE TLV-LENGTH Middle
Middle = MIDDLE-TYPE TLV-LENGTH Inner
Inner = INNER-TYPE TLV-LENGTH INNER-VALUE
You can define the Outer builder:
const buildOuter = new StructBuilder("Outer", TT.Outer)
.add(TT.Middle, "inner", StructFieldType.nest(Inner));
Inner type does not have to encode itself as a TLV. Its encoding result appears as
the TLV-VALUE of the "middle" field TLV.
Turn a TLV class into a field type, where the TLV is nested inside the field.