I was using the 'PutFile' processor, and noticed that you could not specify
the 'filename', and that it is always taken from the input flowfile's
'filename' attribute. I thought it would be useful if it exposed a property
to explicitly set the filename of the processor, defaulting to
`${filename}`.Then I looked at `PutSFTP` and `PutHDFS`, and noticed that they also do not expose the filename as a property. It looks like there might have been a decision made to not expose it in these. As a workaround it seems like I could put an `UpdateAttribute` processor before the `PutFile` that updates 'filename' (and possibly path), but I haven't tried. I wasn't sure if I was getting into some anti-pattern here. Is there a reason not to expose the filename as a property?
