I have simply converted an already existing lambda/cloudformation solution into an easier to use format for aws-cdk users.
The actual lambda code is taken from https://github.com/rosberglinhares/CloudFormationCognitoCustomResources

If you want any additional features just open an issue, or better yet a merge request.

## Usage
Usage if fairly self explanatory, but if you're unsure then here is an example:
The userPool and userPoolClient objects are @aws-cdk/aws-cognito objects that should already be in your stack.
```
let userPoolClientSettings = new UserPoolClientSettings(
    this,
    `userPoolClientSettings`,
    {
    domain: `domain.example.com`,
    userPool: userPool,
    userPoolClient: userPoolClient,
    supportedIdentityProviders: [IdentityProviders.COGNITO],
    callbackURLs: [`https://${cloudFront.domainName}`],
    logoutURLs: [`https://${cloudFront.domainName}`],
    allowedOAuthFlowsUserPoolClient: true,
    allowedOAuthFlows: ["code", "implicit"],
    allowedOAuthScopes: ["openid", "email", "aws.cognito.signin.user.admin"]
    }
);
```