message: Clear nullability warnings in TelemetryObserver
diff: @@ -19,8 +19,8 @@ export interface ITelemetryReporter {
  export class TelemetryObserver {
  private reporter: ITelemetryReporter;
  private platformInfo: PlatformInformation;
  - private solutionId: string;
  - private dotnetInfo: DotnetInfo;
  + private solutionId?: string;
  + private dotnetInfo?: DotnetInfo;
  constructor(platformInfo: PlatformInformation, reporterCreator: () => ITelemetryReporter) {
  this.platformInfo = platformInfo;
  @@ -64,7 +64,7 @@ export class TelemetryObserver {
  }
  private handleTelemetryEventMeasures(event: TelemetryEventWithMeasures) {
  - this.reporter.sendTelemetryEvent(event.eventName, null, event.measures);
  + this.reporter.sendTelemetryEvent(event.eventName, undefined, event.measures);
  }
  private async handleOmnisharpInitialisation(event: OmnisharpInitialisation) {
  @@ -90,16 +90,16 @@ export class TelemetryObserver {
  private handleTestExecutionCountReport(event: TestExecutionCountReport) {
  if (event.debugCounts) {
  - this.reporter.sendTelemetryEvent('DebugTest', null, event.debugCounts);
  + this.reporter.sendTelemetryEvent('DebugTest', undefined, event.debugCounts);
  }
  if (event.runCounts) {
  - this.reporter.sendTelemetryEvent('RunTest', null, event.runCounts);
  + this.reporter.sendTelemetryEvent('RunTest', undefined, event.runCounts);
  }
  }
  private handleProjectConfigurationReceived(event: ProjectConfiguration, telemetryProps: { [key: string]: string }) {
  let projectConfig = event.projectConfiguration;
  - telemetryProps['SolutionId'] = this.solutionId;
  + telemetryProps['SolutionId'] = this.solutionId ?? "";
  telemetryProps['ProjectId'] = projectConfig.ProjectId;
  telemetryProps['SessionId'] = projectConfig.SessionId;
  telemetryProps['OutputType'] = projectConfig.OutputKind?.toString() ?? "";
  