@robnew
In addition to what @janis-ax suggested about setting bulletin level to none on the processor to stop WARN and ERROR level log output from that processor from being sent to the bulletin board, you could also suppress the logging of this processor class via the NiFi logback.xml file. Changing the bulletin level on a processor does not disable logging being produced by your processor code. That logging will still find it way in to the NiFi logs via the logback.xml even with bulletin level set to known.
So though processor you can stop the bulletins and through NiFi's logback.xml you have additional options to send logging produced by your processor class to its own appender or one of the existing appenders already defined in that file.
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Thank you,
Matt