- #5028
- helpers similar to our HTML or tag helpers can use the new singleton to examine or add validation attributes
- in the most common case, helpers add validation attributes to a `TagBuilder`
- separate `DefaultValidationHtmlAttributeProvider` from `DefaultHtmlGenerator`
- avoids creating two instances of the `DefaultHtmlGenerator` singleton
- would be even uglier to require callers to cast an `IHtmlGenerator` to `ValidationHtmlAttributeProvider`
- `[Obsolete]` old `DefaultHtmlGenerator` constructor
- #4116
- generalize rules for `ModelMetadata` creation; minimize metadata changes when Model is updated
- down to a single special case in VDD for `Nullable<T>`
- note existing functional tests did not need to change
- remove `ViewDataDictionary(ViewDataDictionary, object)` constructor; use `new VDD<object>(source, model)`
- allow all `Model` assignments in a view component
- copy-constructed VDD in `ViewComponentContext` previously preserved the source's declared type
nits:
- do not call `virtual SetModel()` method from constructor; now mostly redundant
- logic in copy constructor and `SetModel()` is consistent but different enough to keep code separate
- add some missing doc comments
- fix doc comment property versus type confusion; never need to specify `ViewDataDictionary.` prefix
- fix a few `TemplateBuilder` comments and remove unnecessary `model: null` argument to VDD constructor