move code to boot data module

spring-boot-data/src/main/java/com/baeldung/jsonexception/CustomException.java

@@ -0,0 +1,11 @@
+package com.baeldung.jsonexception;
+
+public class CustomException extends RuntimeException {
+
+    private static final long serialVersionUID = 1L;
+
+    public CustomException() {
+        super("Custom exception message.");
+    }
+
+}

spring-boot-data/src/main/java/com/baeldung/jsonexception/ErrorHandler.java

@@ -0,0 +1,19 @@
+package com.baeldung.jsonexception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ControllerAdvice
+@ResponseBody
+public class ErrorHandler {
+
+    @ExceptionHandler(CustomException.class)
+    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
+    public CustomException handleCustomException(CustomException ce) {
+        return ce;
+    }
+
+}

spring-boot-data/src/main/java/com/baeldung/jsonexception/MainController.java

@@ -0,0 +1,14 @@
+package com.baeldung.jsonexception;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+
+@Controller
+public class MainController {
+
+    @GetMapping("/")
+    public void index() throws CustomException {
+        throw new CustomException();
+    }
+
+}

spring-boot-data/src/test/java/com/baeldung/jsonexception/MainControllerIntegrationTest.java

@@ -0,0 +1,19 @@
+package com.baeldung.jsonexception;
+
+import org.junit.Test;
+
+import com.baeldung.jsonexception.CustomException;
+import com.baeldung.jsonexception.MainController;
+
+public class MainControllerIntegrationTest {
+
+    @Test(expected = CustomException.class)
+    public void givenIndex_thenCustomException() throws CustomException {
+
+        MainController mainController = new MainController();
+
+        mainController.index();
+
+    }
+
+}