Small Caps: ß is rendered as SS

[SFr682k]

Using the latest release of Source Serif Pro, the sharp s (ß) used in German language is rendered as SS when using the small caps shape. However, I would welcome using a “scaled down” version of the uppercase sharp s (ẞ) such as Source Sans Pro does:

[miguelsousa]

Two esses is the correct capitalization of ß, so applying smcp to the word Straßenschild should render as STRASSENSCHILD (two esses) not STRAẞENSCHILD (capital sharp s).

The correct way to get a small cap variant of ẞ (U+1E9E) is by applying c2sc to a word containing this character.

[SFr682k]

Actually, both variants are equally valid since June 2017 (see this Wikipedia article)
The reason why I prefer rendering as STRAẞENSCHILD (with capital sharp s) is, that it keeps words with different meanings, such as „Maße“ and „Masse“, distinguishable in their small caps form.

[frankrolf]

Since both variants are equally valid, this is not an issue. The SS-solution will be more familiar to most users, those who really want the capital variant will know how to get to it.