[LUCENE-7303] Avoid NPE if classField doesn't exist in SNBC

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 6.1
• Component/s: modules/classification
• Lucene Fields: New
• Assignee: Tommaso Teofili
• Reporter: Tommaso Teofili
• Created: 26/May/16 13:57
• Updated: 28/Aug/22 14:58
• Resolved: 26/May/16 14:21

Description

SimpleNaiveBayesClassifier uses MultiFields.getTerms(leafReader, classFieldName). but doesn't check if the resulting Terms is null or not.
While that is unlikely to happen (it doesn't make much sense to use a classifier without specifying an existing class field), it may happen during testing and therefore better to avoid throwing a NPE.