Yeah Magnus.
Sorry i meant pattern => "^%{BWTIME}".
Got the issue resolved. Thanks.
Issue is because of below pattern as GMT +%{INT} is repeated twice.
BWTIME %{YEAR} %{MONTH} %{MONTHDAY} %{TIME} GMT +%{INT}
BWLOG %{BWTIME:timestamp} GMT +%{INT} %{GREEDYDATA:Bwpayload}