fix: handle empty data (#105)

Author: peterdeme

src/main/java/io/getstream/core/models/Data.java

@@ -51,6 +51,9 @@ public <T> Data from(T data) {
 
   public Data from(Map<String, Object> map) {
     checkNotNull(data, "Can't extract data from null");
+    if (map == null || map.isEmpty()) {
+      return this;
+    }
 
     for (Map.Entry<String, Object> entry : map.entrySet()) {
       set(entry.getKey(), entry.getValue());

src/test/java/io/getstream/core/utils/SerializationTest.java

@@ -2,6 +2,7 @@
 
 import static io.getstream.core.utils.Serialization.*;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.google.common.collect.ImmutableMap;
@@ -13,6 +14,7 @@
 import io.getstream.core.models.CollectionData;
 import io.getstream.core.models.EnrichedActivity;
 import io.getstream.core.models.FeedID;
+import io.getstream.core.models.Reaction;
 import java.io.ByteArrayInputStream;
 import java.nio.charset.Charset;
 import java.text.SimpleDateFormat;
@@ -209,6 +211,16 @@ public void emptyMapDeserialization() throws Exception {
         fromJSON(new ByteArrayInputStream(activity.getBytes(Charset.forName("UTF-8"))), type);
   }
 
+  @Test
+  public void emptyDataDeserialization() throws Exception {
+    String reaction = "{ \"data\": {} }";
+    TypeReference<Reaction> type = new TypeReference<Reaction>() {};
+
+    Reaction result =
+        fromJSON(new ByteArrayInputStream(reaction.getBytes(Charset.forName("UTF-8"))), type);
+    assertNotNull(result);
+  }
+
   @Test
   public void creatorAndAnySetterDeserialization() throws Exception {
     String data = "{\"id\":\"id-thing\",\"value\":1,\"extra\":{\"test\":\"test\"}}";