@param out_ the pointer where the creds are to be stored
@param transport a smart transport
@param user the user we saw on the url (if any)
@param methods available methods for authentication
@return the return value of the callback: 0 for no error, git_error_code.GIT_PASSTHROUGH
to indicate that there is no callback registered (or the callback
refused to provide credentials and callers should behave as if no
callback was set), or < 0 for an error
Call the credentials callback for this transport
@param out_ the pointer where the creds are to be stored @param transport a smart transport @param user the user we saw on the url (if any) @param methods available methods for authentication @return the return value of the callback: 0 for no error, git_error_code.GIT_PASSTHROUGH to indicate that there is no callback registered (or the callback refused to provide credentials and callers should behave as if no callback was set), or < 0 for an error