SiteToSite handlers throw errors when transaction cancelled with no data sent

StandardFlowFileCodec and CompressionInputStream (the decoders used by SiteToSite receivers whether compression is disabled or enabled, respectively) each throw an error if the transaction is cancelled with no data being transmitted.

For StandardFlowFileCodec, it is expecting to read the number of attributes for the upcoming flow file, but instead will get the string "RC" followed by a 15 (the cancellation response code). Read as an integer this is larger than the max number of attributes a FlowFile can have, so a ProtocolException is thrown.

For CompressionInputStream, it also expects there to be data incoming, specifically a chunk header for the compressed data. It attempts to read 4 bytes and match them to a sync sequence, which does not match the "RC" + code input, so an IOException is thrown.

These classes should defensively check for the cancellation sequence before proceeding with decoding the data.