Add code examples for Spring Boot nullsafety blog (#137)

* Add code examples for Spring Boot nullsafety blog

* Add required files as per checklist

* Add review comments

* Update build-all.sh

Co-authored-by: Tom Hombergs <tom.hombergs@gmail.com>

spring-boot/spring-boot-null-safe-annotations/src/main/java/io/reflectoring/nullsafety/Application.java

@@ -0,0 +1,13 @@
+package io.reflectoring.nullsafety;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+
+	public static void main(String[] args) {
+		SpringApplication.run(Application.class, args);
+	}
+
+}

spring-boot/spring-boot-null-safe-annotations/src/main/java/io/reflectoring/nullsafety/Employee.java

@@ -0,0 +1,47 @@
+package io.reflectoring.nullsafety;
+
+import java.time.LocalDate;
+
+import org.springframework.lang.NonNull;
+import org.springframework.lang.Nullable;
+
+class Employee {
+
+    @NonNull
+    String id;
+    String name;
+    LocalDate joiningDate;
+    @Nullable
+    String pastEmployment;
+
+    // constructor
+
+    public Employee(String id, String name, LocalDate joiningDate) {
+        this.id = id;
+        this.name = name;
+        this.joiningDate = joiningDate;
+    }
+
+    // standard getters-setters
+
+    String getId() {
+        return id;
+    }
+
+    String getName() {
+        return name;
+    }
+
+    LocalDate getJoiningDate() {
+        return joiningDate;
+    }
+
+    @Nullable
+    String getPastEmployment() {
+        return pastEmployment;
+    }
+
+    void setPastEmployment(@Nullable String pastEmployment) {
+        this.pastEmployment = pastEmployment;
+    }
+}

spring-boot/spring-boot-null-safe-annotations/src/main/java/io/reflectoring/nullsafety/package-info.java

@@ -0,0 +1,4 @@
+@NonNullApi
+package io.reflectoring.nullsafety;
+
+import org.springframework.lang.NonNullApi;

spring-boot/spring-boot-null-safe-annotations/src/main/resources/application.properties

@@ -0,0 +1 @@
+

spring-boot/spring-boot-null-safe-annotations/src/test/java/io/reflectoring/nullsafety/ApplicationTests.java

@@ -0,0 +1,13 @@
+package io.reflectoring.nullsafety;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class ApplicationTests {
+
+	@Test
+	void contextLoads() {
+	}
+
+}

spring-boot/spring-boot-null-safe-annotations/src/test/java/io/reflectoring/nullsafety/EmployeeTest.java

@@ -0,0 +1,25 @@
+package io.reflectoring.nullsafety;
+
+import static org.junit.jupiter.api.Assertions.assertAll;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import java.time.LocalDate;
+
+import org.junit.jupiter.api.Test;
+
+class EmployeeTest {
+
+    @Test
+    void employeeShouldHaveValidDetails() {
+        final Employee employee = new Employee("ID001", "Jane Dia", LocalDate.of(2019, 12, 31));
+        employee.setPastEmployment(null);
+        assertAll(() -> {
+            assertNotNull(employee.getId());
+            assertNotNull(employee.getName());
+            assertNotNull(employee.getJoiningDate());
+            assertNull(employee.getPastEmployment());
+        });
+    }
+
+}