Currently, 
SetClusterParameterInvocation::normalizeParameter() is a public method, which is only used in _configsvrSetClusterParameterCommand implementation.
I believe it is done most probably only to validate the new cluster parameter value.
 
I believe we can simplify the SetClusterParameterInvocation and ConfigsvrSetClusterParameterCommand classes by:

• refactoring the validation out of it,
• minimizing normalizeParameter() signature (currently it has an extra 'skipValidation' parameter to control the validation) and making it private, and
• removing the dependency on SetClusterParameterInvocation from ConfigsvrSetClusterParameterCommand.