feat(option-null-equals): override equals in optional-nullable wrapper (#72)

- Added equals() method: Implemented the equals() method in the OptionalNullable Class. It is used to compare the equality of objects based on the value of wrapped field.

- Added hashCode() method: Implemented the hashCode() method in the OptionalNullable Class. It calculates a unique numeric value, known as the hash code, for the wrapped inner value.

Author: asadali214

src/main/java/io/apimatic/core/types/OptionalNullable.java

@@ -5,9 +5,12 @@
 import java.time.LocalDateTime;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
+
 import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.databind.JsonSerializer;
 import com.fasterxml.jackson.databind.SerializerProvider;
+
 import io.apimatic.core.utilities.LocalDateTimeHelper;
 
 /**
@@ -55,6 +58,24 @@ public static <T> T getFrom(OptionalNullable<T> optionalNullable) {
         return (optionalNullable == null) ? null : optionalNullable.value;
     }
 
+    @Override
+    public int hashCode() {
+        return Objects.hash(value);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == this) {
+            return true;
+        }
+
+        if (obj instanceof OptionalNullable<?>) {
+            return Objects.equals(((OptionalNullable<?>) obj).value, value);
+        }
+
+        return Objects.equals(obj, value);
+    }
+
     /**
      * JsonSerializer for the {@link OptionalNullable} instance. It is used to Serialize an
      * {@link OptionalNullable} as its encapsulated object.

src/test/java/apimatic/core/type/OptionalNullableTest.java

@@ -1,13 +1,18 @@
 package apimatic.core.type;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 import java.io.IOException;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
+
 import org.junit.Test;
 import apimatic.core.models.Rfc1123Date;
 import apimatic.core.models.Rfc1123DateArray;
@@ -21,12 +26,12 @@
 import apimatic.core.models.UnixDate;
 import apimatic.core.models.UnixDateArray;
 import apimatic.core.models.UnixDateMap;
+import io.apimatic.core.types.OptionalNullable;
 import io.apimatic.core.utilities.CoreHelper;
 import io.apimatic.core.utilities.LocalDateTimeHelper;
 
 public class OptionalNullableTest {
 
-
     /**
      * Simple date string.
      */
@@ -91,11 +96,18 @@ public class OptionalNullableTest {
      * An instance of {@link LocalDateTime}.
      */
     private static final LocalDateTime LOCAL_DATE_TIME = LocalDateTime.of(2021, 1, 20, 12, 12, 41);
-
     /**
      * An instance of {@link LocalDate}.
      */
     private static final LocalDate LOCAL_DATE = LocalDate.of(2020, 1, 8);
+    /**
+     * An instance of a number.
+     */
+    private static final int NUMBER_124 = 124;
+    /**
+     * An instance of a number.
+     */
+    private static final int NUMBER_125 = 125;
 
     @Test
     public void testSimpleDate() throws IOException {
@@ -257,4 +269,35 @@ public void testRfc8601DateMapToString() throws IOException {
         String actual = rfc8601DateMap.toString();
         assertEquals(actual, expected);
     }
+
+    @Test
+    public void testEquals() throws IOException {
+        OptionalNullable<String> object1 = OptionalNullable.of("some string");
+        OptionalNullable<String> object2 = OptionalNullable.of("some string");
+        OptionalNullable<String> object3 = OptionalNullable.of("some other string");
+        OptionalNullable<Integer> object4 = OptionalNullable.of(NUMBER_124);
+        OptionalNullable<Integer> object5 = OptionalNullable.of(null);
+
+        assertTrue(object1.equals(object1));
+        assertTrue(object1.equals(object2));
+        assertTrue(object1.equals("some string"));
+        assertTrue(object4.equals(NUMBER_124));
+        assertTrue(object5.equals(null));
+
+        assertFalse(object1.equals(object3));
+        assertFalse(object1.equals(object4));
+        assertFalse(object4.equals(NUMBER_125));
+        assertFalse(object1.equals(null));
+    }
+
+    @Test
+    public void testHashCode() throws IOException {
+        OptionalNullable<String> object1 = OptionalNullable.of("some string");
+        OptionalNullable<String> object2 = OptionalNullable.of("some string");
+        OptionalNullable<Integer> object3 = OptionalNullable.of(NUMBER_124);
+
+        assertEquals(object1.hashCode(), object2.hashCode());
+        assertEquals(object1.hashCode(), Objects.hash("some string"));
+        assertEquals(object3.hashCode(), Objects.hash(NUMBER_124));
+    }
 }