Default values should not disappear in workflow variables in the Configuration view

Current Situation:

When we provide an empty default value ("") for a workflow variable in the configuration, and then click in the configuration view, the empty default value disappears.

Steps to reproduce:

• Create a workflow w1 in your environment.
• Add variables v1 and v2 in your workflow properties.
• Provide empty default values like empty string("") for these variables.
• Click on another folder in the configuration view.
• the empty default value will be disappeared.

Desired Behavior:
The empty default values should not disappear from the configuration.