In Java I can define TestConfiguration in nested class

class Example {

    @Nested
    @SpringBootTest
    public class ExampleNestedTest {

        @TestConfiguration
        public static class TestConfig {

            @Bean 
            public RestTemplate restTemplate() {
                return new RestTemplate();
            }

        }

    }

}

However in Kotlin, the nested test must be inner class, and the nested class in the inner class must also be a inner class

I tried this but got a compiler error

class Example {

    @Nested
    @SpringBootTest
    inner class ExampleNestedTest {

        @TestConfiguration
        class TestConfig {  // This give error 'Class' is prohibited here.
            
            @Bean
            fun restTemplate(): RestTemplate {
                return RestTemplate()
            }

        }
    }
}

I tried adding inner to TestConfig but the bean function will not run.

class Example {

    @Nested
    @SpringBootTest
    inner class ExampleNestedTest {

        @TestConfiguration
        inner class TestConfig {  
            
            @Bean
            fun restTemplate(): RestTemplate { // This bean will not be created as the function will not run
                return RestTemplate()
            }

        }
    }
}

Any idea how to make this to work?