supplement

Supplement attributes before import.

This means prompting the user for things like labels and the like. The needed attributes will have been passed to supplement_prep.

This method prompts the user and fills in the attributes. If the user or cancellable cancels the operation the error should be set with g_io_error_cancelled.

Parameters:

this	the interaction
builder	supplemented attributes
cancellable	optional cancellable object

Returns:

g_tls_interaction_handled if successful or g_tls_interaction_failed