fix changefeed diagnostics (#27091)

### Packages impacted by this PR
@azure/cosmos

### Issues associated with this PR
N/A

### Describe the problem that is addressed by this PR

- Removes check for empty 200 response from backend in async iterator
which earlier led to empty diagnostics
- Add diagnostics to read container in changefeed

### What are the possible designs available to address the problem? If
there are more than one possible design, why was the one in this PR
chosen?


### Are there test cases added in this PR? _(If not, why?)_


### Provide a list of related PRs _(if any)_


### Command used to generate this PR:**_(Applicable only to SDK release
request PRs)_

### Checklists
- [ ] Added impacted package name to the issue description
- [ ] Does this PR needs any fixes in the SDK Generator?** _(If so,
create an Issue in the
[Autorest/typescript](https://github.com/Azure/autorest.typescript)
repository and link it here)_
- [ ] Added a changelog (if necessary)

sdk/cosmosdb/cosmos/src/client/ChangeFeed/ChangeFeedForEpkRange.ts

@@ -49,8 +49,8 @@ export class ChangeFeedForEpkRange<T> implements ChangeFeedPullModelIterator<T>
     this.isInstantiated = false;
   }
 
-  private async setIteratorRid(): Promise<void> {
-    const { resource } = await this.container.read();
+  private async setIteratorRid(diagnosticNode: DiagnosticNodeInternal): Promise<void> {
+    const { resource } = await this.container.readInternal(diagnosticNode);
     this.rId = resource._rid;
   }
 
@@ -156,13 +156,7 @@ export class ChangeFeedForEpkRange<T> implements ChangeFeedPullModelIterator<T>
   public async *getAsyncIterator(): AsyncIterable<ChangeFeedIteratorResponse<Array<T & Resource>>> {
     do {
       const result = await this.readNext();
-      // filter out some empty 200 responses from backend.
-      if (
-        (result.count === 0 && result.statusCode === StatusCodes.NotModified) ||
-        (result.count > 0 && result.statusCode === StatusCodes.Ok)
-      ) {
-        yield result;
-      }
+      yield result;
     } while (this.hasMoreResults);
   }
 
@@ -177,7 +171,7 @@ export class ChangeFeedForEpkRange<T> implements ChangeFeedPullModelIterator<T>
     return withDiagnostics(async (diagnosticNode: DiagnosticNodeInternal) => {
       // validate if the internal queue is filled up with feed ranges.
       if (!this.isInstantiated) {
-        await this.setIteratorRid();
+        await this.setIteratorRid(diagnosticNode);
         await this.fillChangeFeedQueue(diagnosticNode);
       }
 

sdk/cosmosdb/cosmos/src/client/ChangeFeed/ChangeFeedForPartitionKey.ts

@@ -4,7 +4,7 @@ import { InternalChangeFeedIteratorOptions } from "./InternalChangeFeedOptions";
 import { ChangeFeedIteratorResponse } from "./ChangeFeedIteratorResponse";
 import { Container, Resource } from "../../client";
 import { ClientContext } from "../../ClientContext";
-import { Constants, ResourceType, StatusCodes } from "../../common";
+import { Constants, ResourceType } from "../../common";
 import { FeedOptions, Response, ErrorResponse } from "../../request";
 import { ContinuationTokenForPartitionKey } from "./ContinuationTokenForPartitionKey";
 import { ChangeFeedPullModelIterator } from "./ChangeFeedPullModelIterator";
@@ -43,8 +43,8 @@ export class ChangeFeedForPartitionKey<T> implements ChangeFeedPullModelIterator
     }
   }
 
-  private async instantiateIterator(): Promise<void> {
-    await this.setIteratorRid();
+  private async instantiateIterator(diagnosticNode: DiagnosticNodeInternal): Promise<void> {
+    await this.setIteratorRid(diagnosticNode);
     if (this.continuationToken) {
       if (!this.continuationTokenRidMatchContainerRid()) {
         throw new ErrorResponse("The continuation is not for the current container definition.");
@@ -67,8 +67,8 @@ export class ChangeFeedForPartitionKey<T> implements ChangeFeedPullModelIterator
     return true;
   }
 
-  private async setIteratorRid(): Promise<void> {
-    const { resource } = await this.container.read();
+  private async setIteratorRid(diagnosticNode: DiagnosticNodeInternal): Promise<void> {
+    const { resource } = await this.container.readInternal(diagnosticNode);
     this.rId = resource._rid;
   }
 
@@ -85,13 +85,7 @@ export class ChangeFeedForPartitionKey<T> implements ChangeFeedPullModelIterator
   public async *getAsyncIterator(): AsyncIterable<ChangeFeedIteratorResponse<Array<T & Resource>>> {
     do {
       const result = await this.readNext();
-      // filter out some empty 200 responses from backend.
-      if (
-        (result.count === 0 && result.statusCode === StatusCodes.NotModified) ||
-        (result.count > 0 && result.statusCode === StatusCodes.Ok)
-      ) {
-        yield result;
-      }
+      yield result;
     } while (this.hasMoreResults);
   }
 
@@ -101,7 +95,7 @@ export class ChangeFeedForPartitionKey<T> implements ChangeFeedPullModelIterator
   public async readNext(): Promise<ChangeFeedIteratorResponse<Array<T & Resource>>> {
     return withDiagnostics(async (diagnosticNode: DiagnosticNodeInternal) => {
       if (!this.isInstantiated) {
-        await this.instantiateIterator();
+        await this.instantiateIterator(diagnosticNode);
       }
       const result = await this.fetchNext(diagnosticNode);
       return result;

sdk/cosmosdb/cosmos/test/public/integration/changeFeedIterator.spec.ts

@@ -190,7 +190,7 @@ describe("Change Feed Iterator", function (this: Suite) {
         },
         {
           retryCount: 0,
-          metadataCallCount: 2,
+          metadataCallCount: 4,
           locationEndpointsContacted: 1,
           requestStartTimeUTCInMsLowerLimit: startTimestamp,
           requestDurationInMsUpperLimit: getCurrentTimestampInMs() - startTimestamp,