camel-file - tempFileName directory is not auto-created if it is relative before the endpoint path

Hi,

I face a requirement to place temp files in a folder at the same hierarchy as the output folder like this:

• target/data/output/claus.txt
• target/data/temp/claus.tmp

Using a simple route definition like:

from("direct:a").to("file://target/data/output/?tempFileName=../temp/${file:name.noext}.tmp")

If the temp folder does not exist, the GenericFileProducer should auto-create it. However, it only does so correctly for the tempFileName path, if it is relativ "after" the endpoint path. If it is above/before the endpoint path the tempFileName path will be created as a child of the endpoint path instead:

• target/data/output/target/data/temp

This results in a NoSuchFileException when camel tries to write the temp file into the "correct" temp directory target/data/temp afterwards.

A very easy way to reproduce this is to use the 'parentFileUrl' instead of the 'fileUrl' in the createRouteBuilder method of FileProduceTempFileNameTest.java (https://github.com/apache/camel/blob/master/core/camel-core/src/test/java/org/apache/camel/component/file/FileProduceTempFileNameTest.java).