private String getServiceComponentRequestInfoLogMessage(String msg, ServiceComponentHostRequest request, State oldState, State newDesiredState) {
    StringBuilder sb = new StringBuilder();

    sb.append(msg)
      .append(", clusterName=").append(request.getClusterName())
      .append(", serviceName=").append(request.getServiceName())
      .append(", componentName=").append(request.getComponentName())
      .append(", hostname=").append(request.getHostname())
      .append(", currentState=").append(oldState == null ? "null" : oldState)
      .append(", newDesiredState=").append(newDesiredState == null ? "null" : newDesiredState);

    return sb.toString();
  }
Constructs INFO level log message for {@link ServiceComponentHostRequest}
@param msg base  message
@param request the request to construct the log message for
@param oldState current state of the service host component that the request is for.
@param newDesiredState new desired state for the service host component
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/HostComponentResourceProvider.java