S3 ingest will not drop the flowfile created for the directory unless the prefix matches the path

The user can change what is used for calculating the prefix at either template import or feed creation time. If he/she does the problem is getting the prefix value from S3List, which does not write the attribute to the flow file. When DropInvalidFlowFile runs it cannot determine the flow file is invalid if the user has changed the prefix from the default setting and the flow file proceeds. This will throw a stack trace in the log at a later step, when Load Table runs.