Support for dynamic structures

By "dynamic" I mean a structure which I know at runtime.
I wanted to code something like

public class DynStructure extends Structure {
    public DynStructure(Object[] vals) {
         .....
        }
}

and at first I thought that would possible: I'd associate a dummy field name to each value, I'd override getFieldOrder() to return that list (in the order) and I'd override getFieldList() to return my pseudo Fields ... but that's not possible, because Structure relies on reflection and that dependence is difficult to change in a extended class (for one thing Field objects are not instatiable)

Start with Structure, especially getFieldOrder() and getFieldList(), and review how its reflection dependency prevents the proposed DynStructure from supplying runtime-known fields. The issue mentions pseudo Fields and dummy names but does not define an implementation or test path; done would require an agreed design and support for structures whose fields are known only at runtime.