revert: default config in constructor to empty object

experimental/packages/opentelemetry-instrumentation-fetch/src/fetch.ts

@@ -79,7 +79,7 @@ export class FetchInstrumentation extends InstrumentationBase<FetchInstrumentati
   private _usedResources = new WeakSet<PerformanceResourceTiming>();
   private _tasksCount = 0;
 
-  constructor(config: FetchInstrumentationConfig = {}) {
+  constructor(config?: FetchInstrumentationConfig) {
     super('@opentelemetry/instrumentation-fetch', VERSION, config);
   }
 

experimental/packages/opentelemetry-instrumentation/src/platform/browser/instrumentation.ts

@@ -30,7 +30,7 @@ export abstract class InstrumentationBase<
   constructor(
     instrumentationName: string,
     instrumentationVersion: string,
-    config: ConfigType
+    config: ConfigType = {} as ConfigType // The cast here may be wrong as ConfigType may contain required fields
   ) {
     super(instrumentationName, instrumentationVersion, config);
 

experimental/packages/opentelemetry-instrumentation/src/platform/node/instrumentation.ts

@@ -53,7 +53,7 @@ export abstract class InstrumentationBase<
   constructor(
     instrumentationName: string,
     instrumentationVersion: string,
-    config: ConfigType
+    config: ConfigType = {} as ConfigType // The cast here may be wrong as ConfigType may contain required fields
   ) {
     super(instrumentationName, instrumentationVersion, config);