UI Dashboard Page breaks if the backend url changes for backends routing group

[puneet-bdp]

Currently the GatewayWebAppResource.getDistribution function aggregates the query count by backend names. The backend name mapping breaks when the URL of the routing group changes in the backend as the query history URL no longer matches the Backend Gateway ProxyTo entries. Either the query history table should have cascaded updates or the tables should be joined based on backend table primary key.

Error stacktrace:

<title>Error 500 jakarta.servlet.ServletException: java.lang.NullPointerException: element cannot be mapped to a null key</title>

HTTP ERROR 500 jakarta.servlet.ServletException: java.lang.NullPointerException: element cannot be mapped to a null key

URI:	http://trino-gateway.prod.careem-rh.com/webapp/getDistribution
STATUS:	500
MESSAGE:	jakarta.servlet.ServletException: java.lang.NullPointerException: element cannot be mapped to a null key

Caused by:

jakarta.servlet.ServletException: java.lang.NullPointerException: element cannot be mapped to a null key
	at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:412)
	at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:349)
	at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:358)
	at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:312)
	at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:205)
	at org.eclipse.jetty.ee10.servlet.ServletHolder.handle(ServletHolder.java:736)
	at org.eclipse.jetty.ee10.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1614)
	at org.eclipse.jetty.ee10.servlet.ServletHandler$MappedServlet.handle(ServletHandler.java:1547)
	at org.eclipse.jetty.ee10.servlet.ServletChannel.dispatch(ServletChannel.java:824)
	at org.eclipse.jetty.ee10.servlet.ServletChannel.handle(ServletChannel.java:436)
	at org.eclipse.jetty.ee10.servlet.ServletHandler.handle(ServletHandler.java:464)
	at org.eclipse.jetty.server.handler.gzip.GzipHandler.handle(GzipHandler.java:597)
	at org.eclipse.jetty.server.handler.ContextHandler.handle(ContextHandler.java:1060)
	at org.eclipse.jetty.server.Handler$Wrapper.handle(Handler.java:740)
	at org.eclipse.jetty.server.handler.EventsHandler.handle(EventsHandler.java:81)
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:151)
	at org.eclipse.jetty.server.Handler$Wrapper.handle(Handler.java:740)
	at org.eclipse.jetty.server.handler.EventsHandler.handle(EventsHandler.java:81)
	at org.eclipse.jetty.server.Server.handle(Server.java:181)
	at org.eclipse.jetty.server.internal.HttpChannelState$HandlerInvoker.run(HttpChannelState.java:648)
	at org.eclipse.jetty.server.internal.HttpConnection.onFillable(HttpConnection.java:403)
	at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:322)
	at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:99)
	at org.eclipse.jetty.io.SelectableChannelEndPoint$1.run(SelectableChannelEndPoint.java:53)
	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.runTask(AdaptiveExecutionStrategy.java:478)
	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.consumeTask(AdaptiveExecutionStrategy.java:441)
	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.tryProduce(AdaptiveExecutionStrategy.java:293)
	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.run(AdaptiveExecutionStrategy.java:201)
	at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:311)
	at org.eclipse.jetty.util.thread.MonitoredQueuedThreadPool$1.run(MonitoredQueuedThreadPool.java:73)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:979)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.doRunJob(QueuedThreadPool.java:1209)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1164)
	at java.base/java.lang.Thread.run(Thread.java:1583)
Caused by: java.lang.NullPointerException: element cannot be mapped to a null key
	at java.base/java.util.Objects.requireNonNull(Objects.java:259)
	at java.base/java.util.stream.Collectors.lambda$groupingBy$53(Collectors.java:1105)
	at java.base/java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169)
	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1708)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
	at io.trino.gateway.ha.resource.GatewayWebAppResource.getDistribution(GatewayWebAppResource.java:145)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory.lambda$static$0(ResourceMethodInvocationHandlerFactory.java:52)
	at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:146)
	at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:189)
	at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:176)
	at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:93)
	at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:478)
	at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:400)
	at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:81)
	at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:274)
	at org.glassfish.jersey.internal.Errors$1.call(Errors.java:248)
	at org.glassfish.jersey.internal.Errors$1.call(Errors.java:244)
	at org.glassfish.jersey.internal.Errors.process(Errors.java:292)
	at org.glassfish.jersey.internal.Errors.process(Errors.java:274)
	at org.glassfish.jersey.internal.Errors.process(Errors.java:244)
	at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:266)
	at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:253)
	at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:696)
	at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:397)
	... 33 more