The WSDL configuration don't indicate if username/password has already been set. The dialogue popped up always have username/password empty, even if it has already been set for the given WSDL uri (either on this or another processor).
The dialogue could indicate 'Password has been set for http:/asdlkalsdkalskd' - this would also indicate which URI is used for u/p for Basic Auth - which might be a parent of the WSDL uri - additionally the set-password-dialogue should be more like a change-password dialogue.
Related issue (not in Jira) is that the 'Set password' button asks for the credmanager password every time, it should only do so the very first time (ie. use getInstance() instead of getInstance(pw). It might also be confusing to ask for the credman password FIRST when the user is prepared to enter the service password - probably this should be requested AFTERWARDS.
Alex recommends copying the dialogue to avoid the credman-request first.. not sure how that would work compared to the first bit of this issue, as you then would not know if an existing u/p exists in credman.