spring-boot: Failure analysis for a BindException with an unexpected root cause (such as ArrayIndexOutOfBoundsException) is unhelpful

Hi,

I’m using Spring Boot 2.0.2 with Kotlin 1.2.41. I’m trying to use an enum as ConfigurationProperty. I wrote a minimal example application to reproduce the issue: https://github.com/sbueringer/springboot-kotlin-enum/

I have the following ConfigurationProperties:

@Configuration
@ConfigurationProperties(prefix = "custom")
@Validated
class Properties {
    var test = TestEnum.VALUE1
}
enum class TestEnum {VALUE1, VALUE2}

In combination with the following application.yaml:

custom:
  test: VALUE2

I get the following exception on startup:

2018-05-25 06:45:21.848  WARN 22061 --- [  restartedMain] onfigReactiveWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'application': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.boot.context.properties.ConfigurationPropertiesBindException: Error creating bean with name 'properties': Could not bind properties to 'Properties' : prefix=custom, ignoreInvalidFields=false, ignoreUnknownFields=true; nested exception is org.springframework.boot.context.properties.bind.BindException: Failed to bind properties under 'custom.test' to com.example.TestEnum

To reproduce, just clone the repository and startup the SpringBootApplication.

Edit: It seems to work, if I remove the @Validated annotation. Is that intended?