When a secret file is created in credentials plugin, it does not get passed to build node workspace:

 

Steps to reproduce:

1. Add a credentials in form of secret file to Jenkins.

2. Create a freestyle project with one build parameter ${KEY}

3. Setup the project to run on a node

4. Add sh script to build steps : cat ${KEY}

5. Run the project

6. You should see something like the following in project output:
<sub>[test_creds] $ /bin/sh -xe /tmp/jenkins18411461223860606461.sh
+ cat key
cat: key: No such file or directory</sub>