improvement: logging on informer stopping (#1726)

Author: csviri

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/config/ConfigurationService.java

@@ -24,6 +24,8 @@
 /** An interface from which to retrieve configuration information. */
 public interface ConfigurationService {
 
+  Logger log = LoggerFactory.getLogger(ConfigurationService.class);
+
   /**
    * Retrieves the configuration associated with the specified reconciler
    *
@@ -188,9 +190,10 @@ default Optional<InformerStoppedHandler> getInformerStoppedHandler() {
       // hasSynced is checked to verify that informer already started. If not started, in case
       // of a fatal error the operator will stop, no need for explicit exit.
       if (ex != null && informer.hasSynced()) {
-        Logger log = LoggerFactory.getLogger(ConfigurationService.class);
         log.error("Fatal error in informer: {}. Stopping the operator", informer, ex);
         System.exit(1);
+      } else {
+        log.debug("Informer stopped: {}. Error: {}", informer, ex);
       }
     });
   }