DATAMONGO-382 - Fixed potential ClassCastException in MappingMongoConverter.

MappingMongoConverter's convertToMongoType(…) now deals with Sets (and more generally all Collections) correctly.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MappingMongoConverter.java

@@ -813,14 +813,14 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 			return result;
 		}
 
-		if (obj instanceof List) {
-			return maybeConvertList((List<?>) obj);
-		}
-
 		if (obj.getClass().isArray()) {
 			return maybeConvertList(Arrays.asList((Object[]) obj));
 		}
 
+		if (obj instanceof Collection) {
+			return maybeConvertList((Collection<?>) obj);
+		}
+
 		DBObject newDbo = new BasicDBObject();
 		this.write(obj, newDbo);
 		return removeTypeInfoRecursively(newDbo);

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MappingMongoConverterUnitTests.java

@@ -998,6 +998,24 @@ public class MappingMongoConverterUnitTests {
 		assertThat(result.containsKey("foobar"), is(false));
 	}
 
+	/**
+	 * @see DATAMONGO-382
+	 */
+	@Test
+	public void convertsSetToBasicDBList() {
+
+		Address address = new Address();
+		address.city = "London";
+		address.street = "Foo";
+
+		Object result = converter.convertToMongoType(Collections.singleton(address));
+		assertThat(result, is(BasicDBList.class));
+
+		Set<?> readResult = converter.read(Set.class, (BasicDBList) result);
+		assertThat(readResult.size(), is(1));
+		assertThat(readResult.iterator().next(), is(Map.class));
+	}
+
 	static class GenericType<T> {
 		T content;
 	}