`NullPointerException` in `MongoPersistentEntityIndexResolver.appendTextIndexInformation(…)`

[caspianb]

Since upgrading to 2.6.1 I am seeing failures when invoking IndexResolver::resolveIndexFor(...) for some specific entities.

We have a generic pattern using javax.measure classes using an enum which implements an interface defined in this way:

public interface Uom<T extends javax.measure.Quantity.Quantity<T>> {
   javax.measure.Unit.Unit<T> getUnit();
}

public enum UomLength implements Uom<javax.measure.quantity.Length>{
   ...
}

// This is the embedded object type we actually persist.
public class UomMeasure<T extends Uom...> {
   T unit; // the enums are stored here
}

Pre 2.6, index resolution worked just fine on entities containing this object. However, after upgrading to 2.6.1 I get a NullPointerException with the following stack trace (Note: I can "fix" the issue by marking getUnit() as @transient which is an acceptable work-around for our use case -- the persistence mechanism still persists the enum via its string properly and we do not use the annotation based index resolution pattern most of the time).

When I debug into the code and view the state at the time of the NPE I see this:

entity = mappingContext.getPersistentEntity(persistentProperty.getActualType());
persistentProperty.getActualType() -> Integer.class
entity == null

java.lang.NullPointerException
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.appendTextIndexInformation(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.access$100(MongoPersistentEntityIndexResolver.java:78)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver$1.doWithPersistentProperty(MongoPersistentEntityIndexResolver.java:370)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver$1.doWithPersistentProperty(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:360)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.appendTextIndexInformation(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.access$100(MongoPersistentEntityIndexResolver.java:78)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver$1.doWithPersistentProperty(MongoPersistentEntityIndexResolver.java:370)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver$1.doWithPersistentProperty(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:360)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.appendTextIndexInformation(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.access$100(MongoPersistentEntityIndexResolver.java:78)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver$1.doWithPersistentProperty(MongoPersistentEntityIndexResolver.java:370)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver$1.doWithPersistentProperty(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:360)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.appendTextIndexInformation(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.access$100(MongoPersistentEntityIndexResolver.java:78)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver$1.doWithPersistentProperty(MongoPersistentEntityIndexResolver.java:370)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver$1.doWithPersistentProperty(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:360)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.appendTextIndexInformation(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.access$100(MongoPersistentEntityIndexResolver.java:78)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver$1.doWithPersistentProperty(MongoPersistentEntityIndexResolver.java:370)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver$1.doWithPersistentProperty(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:360)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.appendTextIndexInformation(MongoPersistentEntityIndexResolver.java:338)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.potentiallyCreateTextIndexDefinition(MongoPersistentEntityIndexResolver.java:314)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.resolveIndexForEntity(MongoPersistentEntityIndexResolver.java:128)
	at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.resolveIndexFor(MongoPersistentEntityIndexResolver.java:103)
	at org.springframework.data.mongodb.core.index.IndexResolver.resolveIndexFor(IndexResolver.java:69)
	at com.blueyonder.lof.bedrock.tenancy.mongo.SpringMongoContextDatabaseInitializer.lambda$execute$4(SpringMongoContextDatabaseInitializer.java:57)

[christophstrobl]

Thanks for reporting! We'll have a look.

[christophstrobl]

I might be missing something here, but I was not able to reproduce the issue. Could you please provide a complete minimal sample (something that we can unzip or git clone, build, and deploy) that reproduces the problem.

[caspianb]

Thanks for looking into it!

I have attached a sample here:
mongo-index-npe.zip

On 2.5.7 there is no NPE (but I did notice a warning around a cyclic reference inside the underlying javax.measure implementation). However, the only thing actually persisted there is our enum (which is the desired behavior). Everything works fine outside of just the NPE on startup when upgrading to 2.6.1.

[christophstrobl]

Thanks for the sample! I can see now that there's a Map structure involved that should not be traversed. There's already a PR (#3915) available that is related to this issue.