container elements validation ex (#2707)

* container elements validation ex

* comment custom container validation

javaxval/src/main/java/org/baeldung/Customer.java

@@ -0,0 +1,66 @@
+package org.baeldung;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.OptionalInt;
+
+import javax.validation.constraints.Min;
+import javax.validation.constraints.NotBlank;
+import javax.validation.constraints.PositiveOrZero;
+
+public class Customer {
+
+    @NotBlank(message="Name cannot be empty")
+    private String name;
+
+    private List<@NotBlank(message="Address must not be blank") String> addresses;
+    
+    private Integer age;
+    
+    @PositiveOrZero
+    private OptionalInt numberOfOrders;
+    
+    //@NotBlank
+    private Profile profile;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public List<String> getAddresses() {
+        return addresses;
+    }
+
+    public void setAddresses(List<String> addresses) {
+        this.addresses = addresses;
+    }
+
+    public Optional<@Min(18) Integer> getAge() {
+        return Optional.ofNullable(age);
+    }
+
+    public void setAge(Integer age) {
+        this.age = age;
+    }
+
+    public OptionalInt getNumberOfOrders() {
+        return numberOfOrders;
+    }
+
+    public void setNumberOfOrders(OptionalInt numberOfOrders) {
+        this.numberOfOrders = numberOfOrders;
+    }
+
+    public Profile getProfile() {
+        return profile;
+    }
+
+    public void setProfile(Profile profile) {
+        this.profile = profile;
+    }
+
+}