SDK method to set field focused state

[dndrsn]

I'd like to be able to set the focused state of a field so that the vertical bar to the left of the field is blue. It does not appear to be currently possible as far as I can tell. I would imagine a peer method to sdk.field.setInvalid named something like sdk.field.setFocused.

Example:

https://www.contentful.com/developers/docs/extensibility/app-framework/sdk/#field