Add sample configuration with internal bean method

See spring-projects/spring-framework#31985

Author: izeye

src/main/kotlin/com/izeye/helloworld/springbootkotlin/SampleConfiguration.kt

@@ -0,0 +1,25 @@
+package com.izeye.helloworld.springbootkotlin
+
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+
+/**
+ * Sample [Configuration].
+ *
+ * @author Johnny Lim
+ */
+@Configuration
+class SampleConfiguration {
+
+    // This function name will be translated to 'sampleBean$hello_spring_boot_kotlin'.
+    @Bean
+    internal fun sampleBean() = SampleBean()
+
+}
+
+/**
+ * Sample bean.
+ *
+ * @author Johnny Lim
+ */
+class SampleBean