I'm using a LookupRecord Processor to look up a MySQL table. The incoming Flow File Records is in Avro format have a column 'ID_BB_UNIQUE', which should be mapped to the field named 'ID_BB_Unique' in the MySQL table for lookup. After lookup, I return 'ID_BB_Unique' as 'Lookup_ID_BB_Unique' and insert this field value to the Flow File Records. However, the processor throwed me a java.lang.NullPointerException: null value for (non-nullable) string at nifiRecord.Lookup_ID_BB_Unique, while 'ID_BB_UNIQUE' in Flow File is confirmed to not have nulls, and 'ID_BB_Unique' is set to be not null in database. What might be causing this exception and how can I solve it? (If I choose 'Insert Entire Record' as Record Result Contents property in the processor, there is no such exception, but I believe it is not the correct logic to do my lookups and does not solve the problem from root.)   LookupRecord Configuration: LookupService Configuration: Error:   ... View more