def to_s(filter = nil, version = nil)
      log_msg = "#{super(filter, version)} #{trace}"
      log_msg += " from #{id_to_s(@from)}" if filter.nil? || filter.include?(:from)
      log_msg += " to #{id_to_s(@to)}" if filter.nil? || filter.include?(:to)
      log_msg += ", request_from #{id_to_s(@request_from)}" if @request_from && (filter.nil? || filter.include?(:request_from))
      log_msg += ", persistent" if @persistent && (filter.nil? || filter.include?(:persistent))
      log_msg += ", tries #{tries_to_s}" if @tries && !@tries.empty? && (filter.nil? || filter.include?(:tries))
      if filter.nil? || !filter.include?(:results)
        if !@results.nil?
          if @results.is_a?(RightScale::OperationResult)   # Will be true when logging a 'SEND'
            res = @results
          elsif @results.is_a?(Hash) && @results.size == 1 # Will be true when logging a 'RECV' for version 9 or below
            res = @results.values.first
          end
          log_msg += " #{res.to_s}" if res
        end
      else
        log_msg += " results #{@results.inspect}"
      end
      log_msg
    end
def to_s(filter = nil, version = nil)
      log_msg = "#{super(filter, version)} #{trace}"
      log_msg += " from #{id_to_s(@from)}" if filter.nil? || filter.include?(:from)
      log_msg += " to #{id_to_s(@to)}" if filter.nil? || filter.include?(:to)
      log_msg += ", request_from #{id_to_s(@request_from)}" if @request_from && (filter.nil? || filter.include?(:request_from))
      log_msg += ", persistent" if @persistent && (filter.nil? || filter.include?(:persistent))
      log_msg += ", tries #{tries_to_s}" if @tries && !@tries.empty? && (filter.nil? || filter.include?(:tries))
      if filter.nil? || !filter.include?(:results)
        if !@results.nil?
          if @results.is_a?(RightScale::OperationResult)   # Will be true when logging a 'SEND'
            res = @results
          elsif @results.is_a?(Hash) && @results.size == 1 # Will be true when logging a 'RECV' for version 9 or below
            res = @results.values.first
          end
          log_msg += " #{res.to_s}" if res
        end
      else
        log_msg += " results #{@results.inspect}"
      end
      log_msg
    end
Generate log representation

 === Parameters
 filter(Array(Symbol)):: Attributes to be included in output
 version(Symbol|nil):: Version to display: :recv_version, :send_version, or nil meaning none

 === Return
 log_msg(String):: Log representation