JAVA-19547 Move articles from spring-core-2 module to spring-boot modules (#13730)

spring-boot-modules/spring-boot-validation/README.md

@@ -2,3 +2,4 @@
 
 - [Spring Validation in the Service Layer](https://www.baeldung.com/spring-service-layer-validation)
 - [Validation in Spring Boot](https://www.baeldung.com/spring-boot-bean-validation)
+- [Spring Null-Safety Annotations](https://www.baeldung.com/spring-null-safety-annotations)

spring-boot-modules/spring-boot-validation/src/main/java/com/baeldung/nullibility/Person.java

@@ -0,0 +1,33 @@
+package com.baeldung.nullibility;
+
+import org.springframework.lang.NonNull;
+import org.springframework.lang.Nullable;
+
+public class Person {
+    @NonNull
+    private String fullName;
+    @Nullable
+    private String nickName;
+
+    void setFullName(String fullName) {
+        if (fullName != null && fullName.isEmpty()) {
+            fullName = null;
+        }
+        this.fullName = fullName;
+    }
+
+    void setNickName(String nickName) {
+        if (nickName != null && nickName.isEmpty()) {
+            nickName = null;
+        }
+        this.nickName = nickName;
+    }
+
+    String getFullName() {
+        return fullName;
+    }
+
+    String getNickName() {
+        return nickName;
+    }
+}

spring-boot-modules/spring-boot-validation/src/main/java/com/baeldung/nullibility/package-info.java

@@ -0,0 +1,6 @@
+@NonNullApi
+@NonNullFields
+package com.baeldung.nullibility;
+
+import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;