Theia plugins extension doesn't work properly

[olexii4]

Describe the bug

Theia plugins extension doesn't work by default.

Che version

• latest
• nightly
• other: please specify

Steps to reproduce

1. Create a new workspace with the devfile https://raw.githubusercontent.com/eclipse/che-docs/master/devfile.yaml.

http://<your-che-host>/f?url=https://raw.githubusercontent.com/eclipse/che-docs/master/devfile.yaml

2. Press 'Ctrl' + 'Shft' + 'j' in the Theia editor.

Plugins widget will be open with an error: 'Your registry is invalid'

Expected behavior

A list of Theia plugins(the same which is in UD).

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 (please specify)
• other: please specify

Additional context

Tested with cheEditor 'che-theia' (latest and next).

[olexii4]

To get plugins from a repo, we need two requests:

1. <your-che-host>/api/workspace/settings
   and get a responce like this

{
...
cheWorkspacePluginRegistryUrl: "http://plugin-registry-che.192.168.99.100.nip.io/v3",
}

2. <cheWorkspacePluginRegistryUrl>/plugins/

[
 {...},
 {...},
  ...
]

The problem was there:

https://github.com/eclipse/che-theia/blob/852eb4a16c91d93ef7dd087e8dea195c031612eb/extensions/eclipse-che-theia-plugin-ext/src/node/che-plugin-service.ts#L87

        } catch (error) {
            // console.log('ERROR', error);
            // return Promise.reject('Unable to get default plugin registry URI. ' + error.message);

            // A temporary solution. Should throw an error instead.
            this.defaultRegistry = {
                name: 'Eclipse Che plugin registry',
                uri: 'https://che-plugin-registry.openshift.io/v3/plugins/'
            };

Because cheApiService.getWorkspaceSettings() was not implemented at all
https://github.com/eclipse/che-theia/blob/f79cb66c9a57ea9df488b8c62929aecf322f5642/extensions/eclipse-che-theia-plugin-ext/src/plugin/che-workspace.ts#L25

    getSettings(): Promise<che.KeyValue> {
        throw new Error('Method not implemented.');
    }