Add equals and hashCode to picture for easier comparison.

Author: kohlerpop1

API/src/main/java/io/github/jwdeveloper/tiktok/data/models/Picture.java

@@ -30,6 +30,7 @@
 import java.awt.image.BufferedImage;
 import java.io.*;
 import java.net.URL;
+import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 
 public class Picture {
@@ -107,4 +108,14 @@ public Picture asUnsigned() {
     public String toString() {
         return "Picture{link='" + link + "', image=" + image + "}";
     }
+
+    @Override
+    public final boolean equals(Object o) {
+        return o == this || o instanceof Picture picture && picture.link != null && picture.link.equals(link);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(link);
+    }
 }