FullDocumentBeforeChange is NULL

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1

Hi,

I have enabled the pre/post images on the collection -

`[ { 
name: 'Scheduled', 
type: 'collection', 
options: 
{ 
     changeStreamPreAndPostImages: { enabled: true } },
     info: { 
           readOnly: false, 
           uuid: UUID('200292f6-ba33-4f6f-9058-6ac3afa6266f')
     }, 
     idIndex: { 
           v: 2, key: { 
                          _id: 1 
                             }, 
           name: '_id_' 
     } 
} ]

Also, while declaring watch, I have added fullDocumentBeforeChangeLookup -
ChangeStreamOptions options = ChangeStreamOptions.builder() .filter(Aggregation.newAggregation( Aggregation.match(Criteria.where("operationType").in("update","delete")) )) //.fullDocumentLookup(FullDocument.WHEN_AVAILABLE) .fullDocumentBeforeChangeLookup(FullDocumentBeforeChange.WHEN_AVAILABLE) .resumeAfter(resumeToken) .build();

But I am getting the fullDocumentBeforeChange as NULL.
Any suggestion where I am doing wrong.