extensions/microsoft-authentication/src/AADHelper.ts/AzureActiveDirectoryService/refreshToken
class AzureActiveDirectoryService:	private async refreshToken(refreshToken: string, scopeData: IScopeData, sessionId?: string): Promise<IToken> {
		this._refreshingPromise = this.doRefreshToken(refreshToken, scopeData, sessionId);
		try {
			const result = await this._refreshingPromise;
			return result;
		} finally {
			this._refreshingPromise = undefined;
		}
	}