diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/MongoSimpleTypes.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/MongoSimpleTypes.java
index d9467bc54..f0e24af5a 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/MongoSimpleTypes.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/MongoSimpleTypes.java
@@ -45,15 +45,14 @@ public abstract class MongoSimpleTypes {
 	public static final Set<Class<?>> AUTOGENERATED_ID_TYPES;
 
 	static {
-		Set<Class<?>> classes = new HashSet<Class<?>>();
+		Set<Class<?>> classes = new HashSet<>();
 		classes.add(ObjectId.class);
 		classes.add(String.class);
 		classes.add(BigInteger.class);
 		AUTOGENERATED_ID_TYPES = Collections.unmodifiableSet(classes);
 
-		Set<Class<?>> simpleTypes = new HashSet<Class<?>>();
+		Set<Class<?>> simpleTypes = new HashSet<>();
 		simpleTypes.add(Binary.class);
-		simpleTypes.add(BsonObjectId.class);
 		simpleTypes.add(DBRef.class);
 		simpleTypes.add(Decimal128.class);
 		simpleTypes.add(org.bson.Document.class);
@@ -71,7 +70,6 @@ public abstract class MongoSimpleTypes {
 		simpleTypes.add(BsonDbPointer.class);
 		simpleTypes.add(BsonDecimal128.class);
 		simpleTypes.add(BsonDocument.class);
-		simpleTypes.add(BsonDocument.class);
 		simpleTypes.add(BsonDouble.class);
 		simpleTypes.add(BsonInt32.class);
 		simpleTypes.add(BsonInt64.class);
@@ -86,6 +84,7 @@ public abstract class MongoSimpleTypes {
 	}
 
 	private static final Set<Class<?>> MONGO_SIMPLE_TYPES;
+
 	public static final SimpleTypeHolder HOLDER = new SimpleTypeHolder(MONGO_SIMPLE_TYPES, true) {
 
 		@Override
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MongoCustomConversionsUnitTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MongoCustomConversionsUnitTests.java
index 3abe9cf04..37a9623a8 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MongoCustomConversionsUnitTests.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/MongoCustomConversionsUnitTests.java
@@ -25,6 +25,8 @@ import org.junit.Test;
 import org.springframework.core.convert.converter.Converter;
 
 /**
+ * Unit tests for {@link MongoCustomConversions}.
+ *
  * @author Christoph Strobl
  */
 public class MongoCustomConversionsUnitTests {