When encoding a Document, encode all Iterable instances as BSON arrays, rather than just List instances. This is consistent with the behavior of the DBObject encoder,

so this will make it easier to migrate from DBObject to Document

 JAVA-1761

Author: jyemin

bson/src/main/org/bson/codecs/DocumentCodec.java

@@ -166,8 +166,8 @@ private boolean skipField(final EncoderContext encoderContext, final String key)
     private void writeValue(final BsonWriter writer, final EncoderContext encoderContext, final Object value) {
         if (value == null) {
             writer.writeNull();
-        } else if (List.class.isAssignableFrom(value.getClass())) {
-            writeList(writer, (List<Object>) value, encoderContext.getChildContext());
+        } else if (Iterable.class.isAssignableFrom(value.getClass())) {
+            writeIterable(writer, (Iterable<Object>) value, encoderContext.getChildContext());
         } else if (Map.class.isAssignableFrom(value.getClass())) {
             writeMap(writer, (Map<String, Object>) value, encoderContext.getChildContext());
         } else {
@@ -191,7 +191,7 @@ private void writeMap(final BsonWriter writer, final Map<String, Object> map, fi
         writer.writeEndDocument();
     }
 
-    private void writeList(final BsonWriter writer, final List<Object> list, final EncoderContext encoderContext) {
+    private void writeIterable(final BsonWriter writer, final Iterable<Object> list, final EncoderContext encoderContext) {
         writer.writeStartArray();
         for (final Object value : list) {
             writeValue(writer, encoderContext, value);

bson/src/test/unit/org/bson/codecs/DocumentCodecTest.java

@@ -40,6 +40,7 @@
 import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.util.Date;
+import java.util.HashSet;
 import java.util.List;
 
 import static java.util.Arrays.asList;
@@ -90,14 +91,18 @@ public void testPrimitiveBSONTypeCodecs() throws IOException {
     @Test
     public void testIterableEncoding() throws IOException {
         DocumentCodec documentCodec = new DocumentCodec();
-        Document doc = new Document();
-        doc.put("array", asList(1, 2, 3, 4, 5));
+        Document doc = new Document()
+                       .append("list", asList(1, 2, 3, 4, 5))
+                       .append("set", new HashSet<Integer>(asList(1, 2, 3, 4)));
 
         documentCodec.encode(writer, doc, EncoderContext.builder().build());
 
         BsonInput bsonInput = createInputBuffer();
         Document decodedDocument = documentCodec.decode(new BsonBinaryReader(bsonInput), DecoderContext.builder().build());
-        assertEquals(doc, decodedDocument);
+        assertEquals(new Document()
+                     .append("list", asList(1, 2, 3, 4, 5))
+                     .append("set", asList(1, 2, 3, 4)),
+                     decodedDocument);
     }
 
     @Test