Bael 736 ver2 (#1693)

* add notnull

* fix formatting

spring-boot/src/main/java/com/baeldung/dynamicvalidation/model/Customer.java

@@ -4,6 +4,7 @@ import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
+import javax.validation.constraints.NotNull;
 
 import com.baeldung.dynamicvalidation.ContactInfo;
 
@@ -15,6 +16,7 @@ public class Customer {
     private long id;
 
     @ContactInfo
+    @NotNull
     private String contactInfo;
 
     public Customer() {