def instance_names namespace, classname=nil, properties={}
    # if namespace is unset, sfcc will generate invalid XML
    namespace ||= "root/cimv2"
    case namespace
    when Sfcc::Cim::ObjectPath
      objectpath = namespace
      namespace = objectpath.namespace      
    else
      objectpath = objectpath namespace.to_s, classname, properties
    end
    ret = []
    begin
      @client.instance_names(objectpath).each do |path|
        path.namespace = namespace # add missing data
	ret << path
      end
    rescue Sfcc::Cim::ErrorInvalidClass, Sfcc::Cim::ErrorInvalidNamespace
    end
    ret
  end
def instance_names namespace, classname=nil, properties={}
    # if namespace is unset, sfcc will generate invalid XML
    namespace ||= "root/cimv2"
    case namespace
    when Sfcc::Cim::ObjectPath
      objectpath = namespace
      namespace = objectpath.namespace      
    else
      objectpath = objectpath namespace.to_s, classname, properties
    end
    ret = []
    begin
      @client.instance_names(objectpath).each do |path|
        path.namespace = namespace # add missing data
	ret << path
      end
    rescue Sfcc::Cim::ErrorInvalidClass, Sfcc::Cim::ErrorInvalidNamespace
    end
    ret
  end
Return list of Wbem::EndpointReference (object pathes) for instances
  of namespace, classname
 @param namespace : String or Sfcc::Cim::ObjectPath
 @param classname : String (optional)
 @param properties : Hash (optional)