add setters and protected no-arg constructor

cqrs/src/main/java/com/iluwatar/cqrs/domain/model/Author.java

@@ -32,7 +32,7 @@ public class Author {
     this.email = email;
   }
 
-  public Author() {
+  protected Author() {
     super();
   }
 
@@ -40,18 +40,34 @@ public class Author {
     return id;
   }
 
+  public void setId(long id) {
+    this.id = id;
+  }
+
   public String getUsername() {
     return username;
   }
 
+  public void setUsername(String username) {
+    this.username = username;
+  }
+
   public String getName() {
     return name;
   }
 
+  public void setName(String name) {
+    this.name = name;
+  }
+
   public String getEmail() {
     return email;
   }
 
+  public void setEmail(String email) {
+    this.email = email;
+  }
+
   @Override
   public String toString() {
     return "Author [name=" + name + ", email=" + email + "]";

cqrs/src/main/java/com/iluwatar/cqrs/domain/model/Book.java

@@ -34,7 +34,7 @@ public class Book {
     this.author = author;
   }
 
-  public Book() {
+  protected Book() {
     super();
   }
 
@@ -42,18 +42,34 @@ public class Book {
     return id;
   }
 
+  public void setId(long id) {
+    this.id = id;
+  }
+
   public String getTitle() {
     return title;
   }
 
+  public void setTitle(String title) {
+    this.title = title;
+  }
+
   public double getPrice() {
     return price;
   }
 
+  public void setPrice(double price) {
+    this.price = price;
+  }
+
   public Author getAuthor() {
     return author;
   }
 
+  public void setAuthor(Author author) {
+    this.author = author;
+  }
+
   @Override
   public String toString() {
     return "Book [title=" + title + ", price=" + price + ", author=" + author + "]";