This is necessary to enable type-based optimizations with Closure.
Without explicity making these options the same named type, Closure
thinks they are different types and cannot disambiguate the `fromObject`
property.
Today, constructing a new GET request with headers looks like:
const headers = new HttpHeaders({
'My-Header': 'header value',
});
http.get('/url', {headers}).subscribe(...);
This indirection is unnecessary. It'd be more ergonomic to write:
http.get('/url', {headers: {'My-Header': 'header value'}}).subscribe(...);
This commit allows that new syntax, both for HttpHeaders and HttpParams.
In the HttpParams case it also allows construction of HttpParams with a map.
PR Close#18490
