Fix an NullPointerException in Linux Consumption Plan (#1732)

* Don't send statsbeat when cikey is empty or null

* Use a diff Strings

* Remove negation!

Author: heyams

core/src/main/java/com/microsoft/applicationinsights/internal/statsbeat/BaseStatsbeat.java

@@ -21,11 +21,12 @@
 
 package com.microsoft.applicationinsights.internal.statsbeat;
 
-import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Strings;
 import com.microsoft.applicationinsights.TelemetryClient;
 import com.microsoft.applicationinsights.TelemetryConfiguration;
 import com.microsoft.applicationinsights.internal.util.ThreadPoolUtils;
 import com.microsoft.applicationinsights.telemetry.MetricTelemetry;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -64,6 +65,11 @@ private class StatsbeatSender implements Runnable {
         @Override
         public void run() {
             try {
+                // For Linux Consumption Plan, connection string is lazily set.
+                // There is no need to send statsbeat when cikey is empty.
+                if (Strings.isNullOrEmpty(CustomDimensions.get().getCustomerIkey())) {
+                    return;
+                }
                 send();
             }
             catch (Exception e) {

core/src/main/java/com/microsoft/applicationinsights/internal/statsbeat/CustomDimensions.java

@@ -87,6 +87,8 @@ public OperatingSystem getOperatingSystem() {
         return operatingSystem;
     }
 
+    public String getCustomerIkey() { return customerIkey; }
+
     public void setResourceProvider(ResourceProvider resourceProvider) {
         this.resourceProvider = resourceProvider;
     }