Opening project https://github.com/spring-cloud/spring-cloud-function/tree/main/spring-cloud-function-samples/function-sample
After configuring to JDK8, the project still has fatal error.

- The exact error message doesn't in a proper situation
- Should show a notification to tell the user there is a fatal error exists
- Consider to publish diagnostics as a better way to tell the users about the error
Opening project https://github.com/spring-cloud/spring-cloud-function/tree/main/spring-cloud-function-samples/function-sample
After configuring to JDK8, the project still has fatal error.
