otel: fixes NPE

Author: AgraVator

core/src/main/java/io/grpc/internal/InternalSubchannel.java

@@ -589,8 +589,10 @@ public Attributes filterTransport(Attributes attributes) {
     public void transportReady() {
       channelLogger.log(ChannelLogLevel.INFO, "READY");
       subchannelMetrics.recordConnectionAttemptSucceeded(buildLabelSet(
-          addressIndex.getCurrentEagAttributes().get(NameResolver.ATTR_BACKEND_SERVICE),
-          addressIndex.getCurrentEagAttributes().get(LoadBalancer.ATTR_LOCALITY_NAME),
+          getAttributeOrDefault(
+              addressIndex.getCurrentEagAttributes(), NameResolver.ATTR_BACKEND_SERVICE),
+          getAttributeOrDefault(
+              addressIndex.getCurrentEagAttributes(), LoadBalancer.ATTR_LOCALITY_NAME),
           null,
           extractSecurityLevel(
               addressIndex.getCurrentEagAttributes().get(GrpcAttributes.ATTR_SECURITY_LEVEL))
@@ -625,10 +627,10 @@ public void transportShutdown(final Status s) {
           ChannelLogLevel.INFO, "{0} SHUTDOWN with {1}", transport.getLogId(), printShortStatus(s));
       shutdownInitiated = true;
       subchannelMetrics.recordConnectionAttemptFailed(buildLabelSet(
-          addressIndex.getCurrentEagAttributes().get(NameResolver.ATTR_BACKEND_SERVICE),
-          addressIndex.getCurrentEagAttributes().get(LoadBalancer.ATTR_LOCALITY_NAME),
+          getAttributeOrDefault(addressIndex.getCurrentEagAttributes(), NameResolver.ATTR_BACKEND_SERVICE),
+          getAttributeOrDefault(addressIndex.getCurrentEagAttributes(), LoadBalancer.ATTR_LOCALITY_NAME),
           null, null
-      ));
+          ));
       syncContext.execute(new Runnable() {
         @Override
         public void run() {
@@ -670,8 +672,10 @@ public void transportTerminated() {
         filter.transportTerminated(transport.getAttributes());
       }
       subchannelMetrics.recordDisconnection(buildLabelSet(
-          addressIndex.getCurrentEagAttributes().get(NameResolver.ATTR_BACKEND_SERVICE),
-          addressIndex.getCurrentEagAttributes().get(LoadBalancer.ATTR_LOCALITY_NAME),
+          getAttributeOrDefault(
+              addressIndex.getCurrentEagAttributes(), NameResolver.ATTR_BACKEND_SERVICE),
+          getAttributeOrDefault(
+              addressIndex.getCurrentEagAttributes(), LoadBalancer.ATTR_LOCALITY_NAME),
           "Peer Pressure",
           extractSecurityLevel(
               addressIndex.getCurrentEagAttributes().get(GrpcAttributes.ATTR_SECURITY_LEVEL))
@@ -702,6 +706,11 @@ private String extractSecurityLevel(SecurityLevel securityLevel) {
           throw new IllegalArgumentException("Unknown SecurityLevel: " + securityLevel);
       }
     }
+
+    private String getAttributeOrDefault(Attributes attributes, Attributes.Key<String> key) {
+      String value = attributes.get(key);
+      return value == null ? "" : value;
+    }
   }
 
   // All methods are called in syncContext