Javadoc
Allows you to add parameters (typically OAuth parameters such as
oauth_callback or oauth_verifier) which will go directly into the signer,
i.e. you don't have to put them into the request first. The consumer's
SigningStrategy will then take care of writing them to the
correct part of the request before it is sent. This is useful if you want
to pre-set custom OAuth parameters. Note that these parameters are
expected to already be percent encoded -- they will be simply merged
as-is. BE CAREFUL WITH THIS METHOD! Your service provider may decide
to ignore any non-standard OAuth params when computing the signature.