fix(demo): make demo classes serializable

Author: javier-godoy

src/test/java/com/flowingcode/vaadin/addons/gridhelpers/LazyTestData.java

@@ -21,14 +21,16 @@
 package com.flowingcode.vaadin.addons.gridhelpers;
 
 import com.github.javafaker.Faker;
+import java.io.Serializable;
 import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import lombok.Getter;
 import lombok.Setter;
 import org.apache.commons.lang3.StringUtils;
 
-class LazyTestData {
+@SuppressWarnings("serial")
+class LazyTestData implements Serializable {
 
   private static final Faker faker = new Faker();
 

src/test/java/com/flowingcode/vaadin/addons/gridhelpers/Person.java

@@ -20,6 +20,7 @@
 
 package com.flowingcode.vaadin.addons.gridhelpers;
 
+import java.io.Serializable;
 import lombok.AccessLevel;
 import lombok.AllArgsConstructor;
 import lombok.Builder;
@@ -29,12 +30,13 @@
 import lombok.experimental.FieldDefaults;
 import lombok.experimental.NonFinal;
 
+@SuppressWarnings("serial")
 @Getter
 @AllArgsConstructor
 @FieldDefaults(level = AccessLevel.PRIVATE, makeFinal = true)
 @EqualsAndHashCode
 @Builder
-public class Person {
+public class Person implements Serializable {
   @Setter
   @NonFinal
   boolean active;