Che-Theia in Che deployed in an offline environment still need access to static.developers.redhat.com

Describe the bug

Che version

• latest
• nightly
• other: please specify

Steps to reproduce

1. Create Plugin and devfile registries for offline mode
2. Deploy Che with Helm ( or chectl) and configure it to use devfile and plugins registries created above
3. In administration tab create docker registry for the Docker proxy registry server 4. Create a workspace from a web browser that do not have internet access. The workspace starts, the green ball is displayed but Theia ide is not rendred.

Expected behavior

Runtime

• kubernetes (include output of kubectl version)
• Openshift (include output of oc version)
• minikube (include output of minikube version and kubectl version)
• minishift (include output of minishift version and oc version)
• docker-desktop + K8S (include output of docker version and kubectl version)
• other: (please specify)

Screenshots

Installation method

• chectl
• che-operator
• minishift-addon
• I don’t know

Environment

• my computer
  • Windows
  • Linux
  • macOS
• Cloud
  • Amazon
  • Azure
  • GCE
  • other (on premise )
• other: please specify

Additional context

The needed resource to render Theia is a javascript hosted at :
https://static.developers.redhat.com/che/theia_artifacts/vendors.8db588d7bb55e4583128.js

[NM4]

This issue disappeared in Che version 7.7.x but reappeared in version 7.8.0 !

[rkratky]

However if there is a mandatory reason to never use the CDN (which will obviously decrease Theia loading performances), then the NOCDN environment variable can be added in the Theia plugin section of the Devfile, in order to force disabling the CDN completely.

@davidfestal, would it be worth adding this piece of info to https://www.eclipse.org/che/docs/che-7/installing-che-in-restricted-environment/?