theia-code-os/examples/ovsx-router-config.json

{
  "registries": {
    "public": "https://open-vsx.org/",
    "mock": "${self}/mock-open-vsx/"
  },
  "use": [
    "mock",
    "public"
  ],
  "rules": [
    {
      "ifRequestContains": "\\bsample-namespace\\b",
      "use": "mock"
    }
  ]
}