To reproduce:

1. Visit /configure
2. Add a Docker Cloud
3. Add a Docker Agent Template
4. Under "Node Properties", choose "Environment variables"
5. Create an environment variable
6. Press "Apply" to save the config
7. Reload the page
8. Navigate to the Docker Agent Template
9. See that the environment variable defined has disappeared

Expected:

The environment variable is retained when loading the global configuration.

Environment variables are saved correctly when using the plugin, and appear in the created Docker containers as expected — they just don't re-appear when editing the global configuration.