Add Rule validation to check if all fields in rule are present or not.

[galadrielwithlaptop]

First, I want to convey that it is a great demo to showcase the power of Flink.
As I am running this on my environment, if I add a rule whose windowMinutes is not defined, flink throws an exception.

java.lang.NullPointerException
    at com.ververica.field.dynamicrules.Rule.getWindowMillis(Rule.java:46)
    at com.ververica.field.dynamicrules.functions.DynamicAlertFunction.updateWidestWindowRule(DynamicAlertFunction.java:220)
    at com.ververica.field.dynamicrules.functions.DynamicAlertFunction.processBroadcastElement(DynamicAlertFunction.java:144)
    at com.ververica.field.dynamicrules.functions.DynamicAlertFunction.processBroadcastElement(DynamicAlertFunction.java:51)
    at org.apache.flink.streaming.api.operators.co.CoBroadcastWithKeyedOperator.processElement2(CoBroadcastWithKeyedOperator.java:133)
    at org.apache.flink.streaming.runtime.io.StreamTwoInputProcessorFactory.processRecord2(StreamTwoInputProcessorFactory.java:225)
    at org.apache.flink.streaming.runtime.io.StreamTwoInputProcessorFactory.lambda$create$1(StreamTwoInputProcessorFactory.java:194)
    at org.apache.flink.streaming.runtime.io.StreamTwoInputProcessorFactory$StreamTaskNetworkOutput.emitRecord(StreamTwoInputProcessorFactory.java:266)
    at org.apache.flink.streaming.runtime.io.AbstractStreamTaskNetworkInput.processElement(AbstractStreamTaskNetworkInput.java:134)
    at org.apache.flink.streaming.runtime.io.AbstractStreamTaskNetworkInput.emitNext(AbstractStreamTaskNetworkInput.java:105)
    at org.apache.flink.streaming.runtime.io.StreamOneInputProcessor.processInput(StreamOneInputProcessor.java:65)
    at org.apache.flink.streaming.runtime.io.StreamMultipleInputProcessor.processInput(StreamMultipleInputProcessor.java:85)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.processInput(StreamTask.java:542)
    at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.runMailboxLoop(MailboxProcessor.java:231)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.runMailboxLoop(StreamTask.java:831)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:780)
    at org.apache.flink.runtime.taskmanager.Task.runWithSystemExitMonitoring(Task.java:935)
    at org.apache.flink.runtime.taskmanager.Task.restoreAndInvoke(Task.java:914)
    at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:728)
    at org.apache.flink.runtime.taskmanager.Task.run(Task.java:550)
    at java.base/java.lang.Thread.run(Unknown Source)

After analysis, if a new rule is added where windowMinutes is not defined, it throws an error.

I can take this up and add validation check for each new rule. :)

Thanks in advance!!

[afedulov]

Hi @galadrielwithlaptop , sure, feel free to open a PR.