def params
      {}.
      merge!(base_params).
      merge!(tracker_default_params).
      merge!(global_options_params).
      merge!(hit_params).
      merge!(custom_dimensions).
      merge!(custom_metrics).
      merge!(measurement_params).
      reject {|_,v| v.nil?}
    end
def params
      {}.
      merge!(base_params).
      merge!(tracker_default_params).
      merge!(global_options_params).
      merge!(hit_params).
      merge!(custom_dimensions).
      merge!(custom_metrics).
      merge!(measurement_params).
      reject {|_,v| v.nil?}
    end
collects the parameters from options for this hit type