NPE is thrown when running in spring-boot

[ralf0131]

A java application running under spring boot:

2019-03-14 11:46:07.202 ERROR 20364 --- [rter-1-thread-1] com.alibaba.metrics.tomcat.HttpGaugeSet  : Exception occur when getting connector global stats: 

java.lang.NullPointerException: null
  at com.alibaba.metrics.tomcat.HttpGaugeSet.getValueInternal(HttpGaugeSet.java:87)
  at com.alibaba.metrics.CachedMetricSet.refreshIfNecessary(CachedMetricSet.java:48)
  at com.alibaba.metrics.tomcat.HttpGaugeSet$HttpStatGauge.getValue(HttpGaugeSet.java:169)
  at com.alibaba.metrics.reporter.bin.StructMetricManagerReporter.report(StructMetricManagerReporter.java:123)
  at com.alibaba.metrics.reporter.MetricManagerReporter.report(MetricManagerReporter.java:249)
  at com.alibaba.metrics.reporter.MetricManagerReporter$1.run(MetricManagerReporter.java:67)
  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
  at java.util.concurrent.FutureTask.runAndReset$$$capture(FutureTask.java:308)
  at java.util.concurrent.FutureTask.runAndReset(FutureTask.java)
  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
  at java.lang.Thread.run(Thread.java:748)

It looks when populating metrics, there was only 1 connector returned by calling JMXUtils.getObjectNames(globalReqProcessor), however, during runtime, there is 2 connectors returned by calling the same method.

I think the code should check for possible newly added connectors during runtime.