redhat-support-plugin-rhev could not be installed in unattended mode. Upon running setup, it would ask a question regarding using proxy:
"Would you like transactions from the Red Hat Access Plugin sent from the RHEV Manager to be brokered through a proxy server?" There was no parameter to allow skipping this question. This was because the implementation provided an answerfile parameter to ignore setting up a proxy, but it didn't check it's value before it continued. The new implementation checks the value of this environment variable and will only proceed if it is set to True. Additionally, it updates a code considering the value of this parameter.