Hi,

I am working with spring mongodb (1.0.0.RELEASE) and spring webflow, I am getting a null pointer exception:

Code:
java.lang.NullPointerException: null
	at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeMapInternal(MappingMongoConverter.java:535) ~[spring-data-mongodb-1.0.0.RELEASE.jar:na]
	at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeInternal(MappingMongoConverter.java:319) ~[spring-data-mongodb-1.0.0.RELEASE.jar:na]
	at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writeMapInternal(MappingMongoConverter.java:547) ~[spring-data-mongodb-1.0.0.RELEASE.jar:na]
	at org.springframework.data.mongodb.core.convert.MappingMongoConverter.writePropertyInternal(MappingMongoConverter.java:407) ~[spring-data-mongodb-1.0.0.RELEASE.jar:na]
Looking at that line in MappingMongoConverter.writeMapInternal the exception occurs in:
Code:
 if (conversions.isSimpleType(key.getClass())) {
Spring is trying to convert a null Map {null=[]}. That object is contained into a spring webflow messagesMemento object, which means I don't have control over it.

It seems this is a bug. I will be reporting it shortly.

Grettings,
Marco