DATADOC-207 - Empty custom maps get read correctly.

Eagerly detect the map target type by using the TypeInformation instead of falling back to the raw Map interface.

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

@@ -724,7 +724,7 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 		Assert.notNull(dbObject);
 
 		Class<?> customMapType = findTypeToBeUsed(dbObject);
-		Class<?> mapType = customMapType == null ? Map.class : customMapType;
+		Class<?> mapType = customMapType == null ? type.getType() : customMapType;
 
 		Map<Object, Object> map = CollectionFactory.createMap(mapType, dbObject.keySet().size());
 		Map<String, Object> sourceMap = dbObject.toMap();

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

@@ -30,7 +30,7 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
-
+import java.util.SortedMap;
 import org.bson.types.ObjectId;
 import org.joda.time.LocalDate;
 import org.junit.Before;
@@ -396,6 +396,21 @@ public class MappingMongoConverterUnitTests {
 		assertThat(dbo2.get("_id"), is(ObjectId.class));
 	}
 	
+	/**
+	 * @see DATADOC-207
+	 */
+	@Test
+	public void convertsCustomEmptyMapCorrectly() {
+			
+		DBObject map = new BasicDBObject();
+		DBObject wrapper = new BasicDBObject("map", map);
+		
+		ClassWithSortedMap result = converter.read(ClassWithSortedMap.class, wrapper);
+		
+		assertThat(result, is(ClassWithSortedMap.class));
+		assertThat(result.map, is(SortedMap.class));
+	}
+	
 	
 	class ClassWithEnumProperty {
 		
@@ -424,6 +439,10 @@ public class MappingMongoConverterUnitTests {
 		Set<Address> addresses;
 	}
 
+	class ClassWithSortedMap {
+		SortedMap<String, String> map;
+	}
+	
 	class ClassWithMapProperty {
 		Map<Locale, String> map;
 	}