Reason was to have all parameters in one place even if only defaults are used but which are required so that correct XML fragment is generated. Removing them from ClearCaseContext.groovy would mean that the default then have to be set in ScmContext.groovy which practically means, that the parameters are distributed into two places and not one place. IMO it makes the code more concise when the parameter are collected in a single parameter class, here ClearCaseContext.

What do you think?