feature: Implement Serialized Entity Pattern (#2150)

* Add files:
- App.java
- Country.java
- CountryDao.java
- CountrySchemaSql.java
- CountryTest.java
- README.md
- serialize-entity.urm.puml
- pom.xml (inherit from parent pom.xml)
Update files:
- pom.xml (parent pom.xml, add 1 module called serialized-entity)

* Fix duplicated error in pom.xml

* Update:
- pom.xml (module servant, changed by error, now fixed)
- pom.xml (module serialized-entity)

* Update:
- pom.xml (changed, artifactId)

* Update:
- pom.xml

Add:
AppTest.java

* Resolved changes required by the reviewer

Co-authored-by: Ilkka Seppälä <iluwatar@users.noreply.github.com>

serialized-entity/src/test/java/com/iluwatar/serializedentity/CountryTest.java

@@ -0,0 +1,101 @@
+/*
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.serializedentity;
+import org.junit.jupiter.api.Test;
+
+import java.io.*;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class CountryTest {
+
+  @Test
+  void testGetMethod() {
+      Country China = new Country(
+              86,
+              "China",
+              "Asia",
+              "Chinese"
+      );
+
+      assertEquals(86, China.getCode());
+      assertEquals("China", China.getName());
+      assertEquals("Asia", China.getContinents());
+      assertEquals("Chinese", China.getLanguage());
+  }
+
+  @Test
+  void testSetMethod() {
+      Country country = new Country(
+              86,
+              "China",
+              "Asia",
+              "Chinese"
+      );
+
+      country.setCode(971);
+      country.setName("UAE");
+      country.setContinents("West-Asia");
+      country.setLanguage("Arabic");
+
+      assertEquals(971, country.getCode());
+      assertEquals("UAE", country.getName());
+      assertEquals("West-Asia", country.getContinents());
+      assertEquals("Arabic", country.getLanguage());
+  }
+
+  @Test
+  void testSerializable(){
+      // Serializing Country
+      try {
+          Country country = new Country(
+                  86,
+                  "China",
+                  "Asia",
+                  "Chinese");
+          ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("output.txt"));
+          objectOutputStream.writeObject(country);
+          objectOutputStream.close();
+      } catch (IOException e) {
+          e.printStackTrace();
+      }
+
+      // De-serialize Country
+      try {
+          ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream("output.txt"));
+          Country country = (Country) objectInputStream.readObject();
+          objectInputStream.close();
+          System.out.println(country);
+
+          Country China = new Country(
+                  86,
+                  "China",
+                  "Asia",
+                  "Chinese");
+
+          assertEquals(China, country);
+      } catch (Exception e) {
+          e.printStackTrace();
+      }
+  }
+}