refactor: sealed class 도입 및 중복 코드 제거

src/main/kotlin/com/sangdol/validation/DemoController.kt

@@ -22,7 +22,7 @@ class DemoController(
 
     @PostMapping("/wrapper")
     fun wrapper(
-        @RequestBody @Valid request: WrapperRequest
+        @RequestBody @Valid request: DemoRequest.WrapperRequest
     ): ResponseEntity<Void> {
         demoService.doSomething(request)
 
@@ -31,7 +31,7 @@ class DemoController(
 
     @PostMapping("/primitive")
     fun primitive(
-        @RequestBody @Valid request: PrimitiveRequest
+        @RequestBody @Valid request: DemoRequest.PrimitiveRequest
     ): ResponseEntity<Void> {
         demoService.doSomething(request)
 

src/main/kotlin/com/sangdol/validation/DemoDTO.kt

@@ -3,19 +3,23 @@ package com.sangdol.validation
 import jakarta.validation.constraints.NotNull
 
 
-data class WrapperRequest(
-    @NotNull
-    val withAnnotation: String,
+sealed class DemoRequest {
 
-    val withoutAnnotation: String
-)
+    abstract val withAnnotation: Any
+    abstract val withoutAnnotation: Any
 
-data class PrimitiveRequest(
-    @NotNull
-    val withAnnotation: Int,
+    data class WrapperRequest(
+        @NotNull
+        override val withAnnotation: String,
+        override val withoutAnnotation: String
+    ) : DemoRequest()
 
-    val withoutAnnotation: Int
-)
+    data class PrimitiveRequest(
+        @NotNull
+        override val withAnnotation: Int,
+        override val withoutAnnotation: Int
+    ) : DemoRequest()
+}
 
 data class SolutionForPrimitive(
     @NotNull

src/main/kotlin/com/sangdol/validation/DemoService.kt

@@ -14,13 +14,8 @@ class DemoService(
         request.value?.let { log.info { "value: ${request.value}" } }
     }
 
-    fun doSomething(request: WrapperRequest) {
+    fun doSomething(request: DemoRequest) {
         log.info { "wrapper requests: $request." }
         log.info { "withAnnotation: ${request.withAnnotation}, withoutAnnotation: ${request.withoutAnnotation}" }
     }
-
-    fun doSomething(request: PrimitiveRequest) {
-        log.info { "primitive requests: $request." }
-        log.info { "withAnnotation: ${request.withAnnotation}, withoutAnnotation: ${request.withoutAnnotation}" }
-    }
 }