Derived type deserialization test

Author: Caitlin Bales (MSFT)

src/test/java/com/microsoft/graph/serializer/DefaultSeralizerTests.java

@@ -7,9 +7,11 @@
 import org.junit.Test;
 
 import com.microsoft.graph.models.extensions.Drive;
+import com.microsoft.graph.models.extensions.FileAttachment;
 import com.microsoft.graph.models.generated.RecurrenceRangeType;
 import com.microsoft.graph.models.generated.BaseRecurrenceRange;
 import com.microsoft.graph.logger.DefaultLogger;
+import com.microsoft.graph.models.extensions.Attachment;
 import com.microsoft.graph.models.extensions.DateOnly;
 
 public class DefaultSeralizerTests {
@@ -64,5 +66,16 @@ public void testRecurrenceRangeSerialization() throws Exception {
         assertNotNull(jsonOut);
         assertEquals(expected, jsonOut);
     }
-
+	
+	@Test
+	public void testDeserializeDerivedType() throws Exception {
+		final DefaultSerializer serializer = new DefaultSerializer(new DefaultLogger());
+		String source = "{\"@odata.context\": \"/attachments/$entity\",\"@odata.type\": \"#microsoft.graph.fileAttachment\",\"id\": \"AAMkAGQ0MjBmNWVkLTYxZjUtNDRmYi05Y2NiLTBlYjIwNzJjNmM1NgBGAAAAAAC6ff7latYeQqu_gLrhSAIhBwCF7iGjpaOmRqVwbZc-xXzwAAAAAAEMAACF7iGjpaOmRqVwbZc-xXzwAABQStA0AAABEgAQAFbGmeisbjtLnQdp7kC_9Fk=\",\"lastModifiedDateTime\": \"2018-01-23T21:50:22Z\",\"name\": \"Test Book.xlsx\",\"contentType\": \"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet\",\"size\": 8457,\"isInline\": false,\"contentId\": null,\"contentLocation\": null,\"contentBytes\": \"bytedata\"}";
+		Attachment result = serializer.deserializeObject(source, Attachment.class);
+		
+		assert(result instanceof FileAttachment);
+		
+		FileAttachment fileAttachment = (FileAttachment) result;
+		assertNotNull(fileAttachment.contentBytes);
+	}
 }