Bonita 7.0.2

Complete a task with an external form.

How can I use an external form to display and send information to the data model in a process?

Bonita Home and properties in Bonita 7.0.2

The documentation says :
"The bonita.home system property points to the root directory for a client application of Bonita BPM. The directory contains a client subdirectory, which contains a conf subdirectory. The conf subdirectory contains the file."

A FILE object defined in the contract is always madatory? Bonita 7.0.2

I am testing this process to upload and download files. I have set the mandatory property of upload widget to false.
When I throw the process, if I do not select a file in "Step Upload" and click "submit" the process does not continue to the next task and this message catalina log: