code: public static PerformanceMetrics createNew(String action, String descriptor, String correlationId) {
      return new PerformanceMetrics(KEY_GEN.getAndIncrement(), 0, action, null, descriptor, correlationId);
    }
docs: Creates new instance of performance metrics. Generates new metrics key and assigns zero level.
  @param action a short name of measured operation, typically a first prefix of descriptor
  @param descriptor a full description of measured operation
  @param correlationId a reference to the request, which caused the operation
  @return PerformanceMetrics a new instance of performance metrics