Improve Javadoc for executeActionsEmail REST endpoint to list all supported actions

[ChristopheGustave]

Hi maintainers,

I'd like to suggest a documentation enhancement to improve clarity around the usage of the executeActionsEmail endpoint in UserResource.java.

Currently, the Javadoc for this method outlines its purpose but does not specify the valid values that can be passed in the actions parameter. These values correspond to UserModel.RequiredAction, but this link isn't immediately clear to users unfamiliar with Keycloak's internal model.

As a result, developers may run into confusion or errors when trying to trigger specific user actions like resetting a password, configuring TOTP, or verifying email.

My proposal is to update the Javadoc for UserResource.executeActionsEmail() to:

1. List all valid RequiredAction values (e.g., UPDATE_PASSWORD, CONFIGURE_TOTP, etc.)
2. Briefly describe the purpose of each action
3. Include an example JSON payload for making a request via the Admin REST API or Admin CLI

Please let me know if this improvement would be welcome. I’d be happy to submit a PR with the proposed changes.

Thanks,
Christophe Gustave