Made MediaMetadata serializable, added a test to confirm

extensions/data-transfer/portability-data-transfer-google/src/main/java/org/datatransferproject/datatransfer/google/mediaModels/MediaMetadata.java

@@ -17,9 +17,10 @@
 package org.datatransferproject.datatransfer.google.mediaModels;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
+import java.io.Serializable;
 
 /** Metadata about a {@code MediaItem}. */
-public class MediaMetadata {
+public class MediaMetadata implements Serializable {
 
   @JsonProperty("photo")
   private Photo photo;

extensions/data-transfer/portability-data-transfer-google/src/test/java/org/datatransferproject/datatransfer/google/mediaModels/GoogleAlbumTest.java

@@ -17,7 +17,7 @@
 import org.junit.Test;
 public class GoogleAlbumTest {
   private static final ObjectMapper mapper = new ObjectMapper()
-      .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+      .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, true);
 
   @Test
   public void googleAlbum_isSerializable() {

extensions/data-transfer/portability-data-transfer-google/src/test/java/org/datatransferproject/datatransfer/google/mediaModels/MediaMetadataTest.java

@@ -0,0 +1,39 @@
+package org.datatransferproject.datatransfer.google.mediaModels;
+
+import static org.junit.Assert.assertTrue;
+
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.io.ByteArrayOutputStream;
+import java.io.ObjectOutputStream;
+import org.junit.Test;
+import static java.lang.String.format;
+
+public class MediaMetadataTest {
+  private static final ObjectMapper mapper = new ObjectMapper()
+      .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, true);
+
+  @Test
+  public void mediaMetadata_isSerializable() {
+    String photoStringJSON = "{\"cameraMake\":\"testMake\", \"cameraModel\":\"testModel\","
+        + "\"focalLength\":\"5.0\", \"apertureFNumber\":\"2.0\", \"isoEquivalent\":\"8.0\", "
+        + "\"exposureTime\":\"testExposureTime\"}";
+    String videoStringJSON = "{\"cameraMake\":\"testMake\", \"cameraModel\":\"testModel\","
+        + "\"fps\": \"30\", \"status\": \"READY\"}";
+    String mediaMetadataStringJSON = format("{\"photo\": %s, \"video\": %s}", photoStringJSON, videoStringJSON);
+
+    boolean serializable = true;
+    // Turning an object into a byte array can only be done if the class is serializable.
+    try {
+      MediaMetadata mediaMetadata = mapper.readValue(mediaMetadataStringJSON, MediaMetadata.class);
+      ByteArrayOutputStream bos = new ByteArrayOutputStream();
+      ObjectOutputStream oos = new ObjectOutputStream(bos);
+      oos.writeObject(mediaMetadata);
+      oos.flush();
+      byte [] data = bos.toByteArray();
+    } catch (Exception e ) {
+      serializable = false;
+    }
+    assertTrue(serializable);
+  }
+}