telemetry(amazonq): fix userTriggerDecision not being sent if service returns empty (#6053)

## Problem
there are 2 scenarios where we consider "Empty"
1. empty list of suggestion : `[]`
2. non empty list of suggestion with empty content: `['', '']`


Currently, only (2) will have plugins send out `userTriggerDecision`
event whereas (1) doesn't.

## Solution


---

<!--- REMINDER: Ensure that your PR meets the guidelines in
CONTRIBUTING.md -->

License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Author: Will-ShaoHua

packages/core/src/codewhisperer/service/recommendationHandler.ts

@@ -390,6 +390,7 @@ export class RecommendationHandler {
 
         // send Empty userDecision event if user receives no recommendations in this session at all.
         if (invocationResult === 'Succeeded' && nextToken === '') {
+            // case 1: empty list of suggestion []
             if (session.recommendations.length === 0) {
                 session.requestIdList.push(requestId)
                 // Received an empty list of recommendations
@@ -404,7 +405,8 @@ export class RecommendationHandler {
                     session.requestContext.supplementalMetadata
                 )
             }
-            if (!this.hasAtLeastOneValidSuggestion(typedPrefix)) {
+            // case 2: non empty list of suggestion but with (a) empty content or (b) non-matching typeahead
+            else if (!this.hasAtLeastOneValidSuggestion(typedPrefix)) {
                 this.reportUserDecisions(-1)
             }
         }

packages/core/src/codewhisperer/util/telemetryHelper.ts

@@ -99,6 +99,8 @@ export class TelemetryHelper {
         language: CodewhispererLanguage,
         supplementalContextMetadata?: CodeWhispererSupplementalContext | undefined
     ) {
+        const selectedCustomization = getSelectedCustomization()
+
         telemetry.codewhisperer_userDecision.emit({
             codewhispererCompletionType: 'Line',
             codewhispererGettingStartedTask: session.taskType,
@@ -117,6 +119,41 @@ export class TelemetryHelper {
             credentialStartUrl: AuthUtil.instance.startUrl,
             traceId: this.traceId,
         })
+
+        telemetry.codewhisperer_userTriggerDecision.emit({
+            codewhispererAutomatedTriggerType: session.autoTriggerType,
+            codewhispererClassifierResult: this.classifierResult,
+            codewhispererClassifierThreshold: this.classifierThreshold,
+            codewhispererCompletionType: 'Line',
+            codewhispererCursorOffset: session.startCursorOffset,
+            codewhispererCustomizationArn: selectedCustomization.arn === '' ? undefined : selectedCustomization.arn,
+            codewhispererFeatureEvaluations: FeatureConfigProvider.instance.getFeatureConfigsTelemetry(),
+            codewhispererFirstRequestId: requestIdList[0],
+            codewhispererGettingStartedTask: session.taskType,
+            codewhispererLanguage: language,
+            codewhispererLineNumber: session.startPos.line,
+            codewhispererPreviousSuggestionState: this.prevTriggerDecision,
+            codewhispererSessionId: sessionId,
+            codewhispererSuggestionCount: 0,
+            codewhispererSuggestionImportCount: 0,
+            codewhispererSuggestionState: 'Empty',
+            codewhispererSupplementalContextIsUtg: supplementalContextMetadata?.isUtg,
+            codewhispererSupplementalContextLength: supplementalContextMetadata?.contentsLength,
+            // eslint-disable-next-line id-length
+            codewhispererSupplementalContextStrategyId: supplementalContextMetadata?.strategy,
+            codewhispererSupplementalContextTimeout: supplementalContextMetadata?.isProcessTimeout,
+            codewhispererTimeSinceLastDocumentChange: this.timeSinceLastModification
+                ? this.timeSinceLastModification
+                : undefined,
+            codewhispererTimeSinceLastUserDecision: this.lastTriggerDecisionTime
+                ? performance.now() - this.lastTriggerDecisionTime
+                : undefined,
+            codewhispererTimeToFirstRecommendation: session.timeToFirstRecommendation,
+            codewhispererTriggerType: session.triggerType,
+            codewhispererTypeaheadLength: this.typeAheadLength,
+            credentialStartUrl: AuthUtil.instance.startUrl,
+            traceId: this.traceId,
+        })
     }
 
     /**