refactor: set default service name in utility class

Previously the Metric and Tracer classes did not set a service name if
one was not provided. There was no default service name.
This commit sets a default service name in the Utility class, and
updates the Tracer, Metric and Logger classes to use it.

Author: ConnorKirk

packages/commons/src/Utility.ts

@@ -56,8 +56,8 @@
  * ```
  */
 export class Utility {
-  
   private coldStart: boolean = true;
+  private readonly defaultServiceName: string = 'service_undefined';
 
   public getColdStart(): boolean {
     if (this.coldStart) {
@@ -69,6 +69,10 @@ export class Utility {
     return false;
   }
 
+  public getDefaultServiceName(): string {
+    return this.defaultServiceName;
+  }
+
   public isColdStart(): boolean {
     return this.getColdStart();
   }

packages/logger/src/Logger.ts

@@ -118,8 +118,6 @@ class Logger extends Utility implements ClassThatLogs {
 
   private static readonly defaultLogLevel: LogLevel = 'INFO';
 
-  private static readonly defaultServiceName: string = 'service_undefined';
-
   // envVarsService is always initialized in the constructor in setOptions()
   private envVarsService!: EnvironmentVariablesService;
 
@@ -786,7 +784,7 @@ class Logger extends Utility implements ClassThatLogs {
           this.getEnvVarsService().getCurrentEnvironment(),
         sampleRateValue: this.getSampleRateValue(),
         serviceName:
-          serviceName || this.getCustomConfigService()?.getServiceName() || this.getEnvVarsService().getServiceName() || Logger.defaultServiceName,
+          serviceName || this.getCustomConfigService()?.getServiceName() || this.getEnvVarsService().getServiceName() || this.getDefaultServiceName(),
       },
       persistentLogAttributes,
     );

packages/metrics/src/Metrics.ts

@@ -473,7 +473,7 @@ class Metrics extends Utility implements MetricsInterface {
   private setService(service: string | undefined): void {
     const targetService = (service ||
       this.getCustomConfigService()?.getServiceName() ||
-      this.getEnvVarsService().getServiceName()) as string;
+      this.getEnvVarsService().getServiceName()) as string || this.getDefaultServiceName();
     if (targetService.length > 0) {
       this.setDefaultDimensions({ service: targetService });
     }

packages/tracer/src/Tracer.ts

@@ -128,7 +128,7 @@ class Tracer extends Utility implements TracerInterface {
   // envVarsService is always initialized in the constructor in setOptions()
   private envVarsService!: EnvironmentVariablesService;
 
-  private serviceName?: string;
+  private serviceName!: string;
 
   private tracingEnabled: boolean = true;
 
@@ -189,7 +189,7 @@ class Tracer extends Utility implements TracerInterface {
    * 
    */
   public addServiceNameAnnotation(): void {
-    if (!this.isTracingEnabled() || this.serviceName === undefined) {
+    if (!this.isTracingEnabled()) {
       return;
     }
     this.putAnnotation('Service', this.serviceName);
@@ -836,6 +836,7 @@ class Tracer extends Utility implements TracerInterface {
 
       return;
     }
+    this.serviceName = this.getDefaultServiceName();
   }
 
   /**