DATAMONGO-2011 - Relax type check when mapping collections.

Author: christophstrobl

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

@@ -982,13 +982,12 @@ private Object readCollectionOrArray(TypeInformation<?> targetType, Collection<?
 				items.add(read(componentType, (BasicDBObject) element, path));
 			} else {
 
-				if (element instanceof Collection) {
+				if (!Object.class.equals(rawComponentType) && element instanceof Collection) {
 					if (!rawComponentType.isArray() && !ClassUtils.isAssignable(Iterable.class, rawComponentType)) {
 						throw new MappingException(
 								String.format(INCOMPATIBLE_TYPES, element, element.getClass(), rawComponentType, path));
 					}
 				}
-
 				if (element instanceof List) {
 					items.add(readCollectionOrArray(componentType, (Collection<Object>) element, path));
 				} else {

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

@@ -1883,6 +1883,15 @@ public void readsImmutableObjectCorrectly() {
 		assertThat(result.witherUsed).isTrue();
 	}
 
+	@Test // DATAMONGO-2011
+	public void readsNestedListsToObjectCorrectly() {
+
+		List<String> values = Arrays.asList("ONE", "TWO");
+		org.bson.Document source = new org.bson.Document("value", Collections.singletonList(values));
+
+		assertThat(converter.read(Attribute.class, source).value).isInstanceOf(List.class);
+	}
+
 	static class GenericType<T> {
 		T content;
 	}