GGSSchemeBase blindly assumes that SPNEGO is always used

Lines 248 to 249 say:

buffer.append(": Negotiate ");
buffer.append(tokenstr);

This is incorrect. Since this is an abstract class the actual scheme must be passed by the extending class through the super constructor. Same applies for the getSchemeName method. Correct behavior is implemented in the httpclient-win module and can be used as a template.