It seems that it is impossible to have database-stored null or empty strings for domain properties annotated with @Facet.

I tried the configuration below:
{{
@Entity
@Indexed
@Table(name = "issuer")
public class IndexedObject implements Serializable {

@Column
@Fields(

)
@Facet(forField = "city_na")
private String city;

}
}}

a call to persist on a newly created IndexedObject() will yield the following exception:

{{
Caused by: java.lang.NullPointerException
at org.hibernate.search.engine.spi.DocumentBuilderIndexedEntity.addFacetDocValues(DocumentBuilderIndexedEntity.java:664)
at org.hibernate.search.engine.spi.DocumentBuilderIndexedEntity.buildDocumentFieldsForProperties(DocumentBuilderIndexedEntity.java:646)
at org.hibernate.search.engine.spi.DocumentBuilderIndexedEntity.buildDocumentFields(DocumentBuilderIndexedEntity.java:463)
at org.hibernate.search.engine.spi.DocumentBuilderIndexedEntity.getDocument(DocumentBuilderIndexedEntity.java:395)
at org.hibernate.search.engine.spi.DocumentBuilderIndexedEntity.createAddWork(DocumentBuilderIndexedEntity.java:299)
at org.hibernate.search.engine.spi.DocumentBuilderIndexedEntity.addWorkToQueue(DocumentBuilderIndexedEntity.java:240)
}}

The documentation states (5.4.1.1) that "null values should be avoided.", not that null values are not supported. I do understand that null/empty fields cannot be indexed, but I thought that was the goal of the @Field property indexNullAs, in order to have a marker in the index for null values. However it seems that the conversion from null in the index does not take this setting into account.

The only bypass that I have found is to define a default, non-null, non-empty value to any indexed property used in conjunction with @Facet within my domain object. That is extremely inconvenient since I would have to handle that specific "null" (for example) value throughout my application instead of only when filtering on facets.

Please let me know if I have missed something, or if there is a configuration bypass.

Thanks,