我正在创建一个websocket API网关，并且具有以下路线：
$ connect wich使用AWS_IAM授权（签名版本4）
$ disconnect
$ default
sendmessage
我遇到的问题如下，在连接lambda中，RequestContext.Identity具有所有有效的属性（类似于cognito身份ID的文件），但是当我通过websocket调用sendmessage时，RequestContext.Identity.SourceIp和RequestContext.Identity.UserAgent已填充，是否有任何方法可以在sendmessage路由中获取CognitoIdentityId？
$ connect RequestContext.Identity为
"CognitoIdentityPoolId": "eu-central-1:a520283f-1353-43d7-b441-b0fc5152b027",
"AccountId": "396151468972",
"CognitoIdentityId": "eu-central-1:1a9421b5-3361-4da9-8adf-22cf5d92eeb9",
"Caller": "AROAVYPDXWOWIJFD6FIYE:CognitoIdentityCredentials",
"ApiKey": null,
"SourceIp": "1.15.1.22",//modified
"CognitoAuthenticationType": "authenticated",
"CognitoAuthenticationProvider": "cognito-idp.eu-central-1.amazonaws.com/eu-central-1_gPSLBBoLn,cognito-idp.eu-central-1.amazonaws.com/eu-central-1_gPSLBBoLn:CognitoSignIn:7812ef00-44cd-4c3c-a8f7-df2434441e67",
"UserArn": "arn:aws:sts::396151468972:assumed-role/Cognito_NanoVoltsAuth_Role/CognitoIdentityCredentials",
"UserAgent": "BestHTTP 1.12.3",
"User": "AROAVYPDXWOWIJFD6FIYE:CognitoIdentityCredentials"
sendmessage RequestContext.Identity为
"CognitoIdentityPoolId": null,
"AccountId": null,
"CognitoIdentityId": null,
"Caller": null,
"ApiKey": null,
"SourceIp": "1.15.1.22",//modified
"CognitoAuthenticationType": null,
"CognitoAuthenticationProvider": null,
"UserArn": null,
"UserAgent": "BestHTTP 1.12.3",
"User": null