Java LS "Classpath is incomplete" warning when loading petclinic

Description

After I have created a workspace using the following devfile

---
specVersion: 0.0.1
name: petclinic-dev-environment
projects:
  - name: petclinic
    source:
      type: git
      location: 'https://github.com/spring-projects/spring-petclinic.git'
components:
  - type: kubernetes
    alias: mvn-container
    reference: https://gist.githubusercontent.com/l0rd/52eda1d1b57878a218cba17c0c93a477/raw/9a2d56e777d22e77c25c45744caea35bb62d8688/petclinic.yaml
    selector:
      app.kubernetes.io/component: webapp
  - type: kubernetes
    reference: https://gist.githubusercontent.com/l0rd/52eda1d1b57878a218cba17c0c93a477/raw/9a2d56e777d22e77c25c45744caea35bb62d8688/petclinic.yaml
    selector:
      app.kubernetes.io/component: database
  - type: chePlugin
    id: redhat/java/0.45.0
  - type: chePlugin
    id: redhat/vscode-yaml/0.4.0
commands:
  - name: build
    actions:
      - type: exec
        component: mvn-container
        command: mvn package
        workdir: /projects/spring-petclinic

a classpath incomplete warning is shown every time a Java file is opened:

Reproduction Steps

Start a workspace using this devfile:

chectl workspace:start --devfile=https://gist.githubusercontent.com/l0rd/52eda1d1b57878a218cba17c0c93a477/raw/8ef7ff447a7164215395d6bc7d70b49363ebae86/devfile.yaml

OS and version:

macOS / minikube / nightly che-server / chectl / helm / jtd ls 0.45.0

[sunix]

@rhopp @dmytro-ndp @eclipse/eclipse-che-qa @l0rd I guess we can close that issue and do not merge https://github.com/eclipse/che-theia/pull/412

[JPinkney]

Since this is the last blocker I wanted to do a write up explaining everything I’ve found so far:

First, I’m not sure if the issue has disappeared as a result of some other fix or if there’s another issue that’s the problem such as internet speed etc because I cannot reproduce on 7.0.0 rc 5 with latest che-theia using the devfile given. However, I can reproduce the issue by changing the devfile to clone no projects and then running > git clone https://github.com/spring-projects/spring-petclinic in the command palette when theia is loaded.

But in an attempt to switch to multi root workspaces to mitigate this in the future, with the multi root workspace code Thomas gave me [1] there seems to be a race condition between when the git clone happens and when the java language server registers the workspace/didUpdateWorkspaceFolders with the client. It seems to me that if a project is finished cloning before the java language server sends client/registerCapability with workspace/didUpdateWorkspaceFolders to the client then the client doesn’t actually send the changed folder to the java language server. I believe this is the reason why cloning a small java project such as the https://github.com/che-samples/console-java-simple will get a classpath issue with these new code changes. However, if you are trying to clone a larger java project, such as https://github.com/angelozerr/lsp4xml it does not seem to be the case and you won’t get the classpath issue.

I believe this issue is caused because che-7.0.0 theia branch does not have the vscode activation events implemented and thus vscode-java is getting started on workspace start which is then starting the java language server, rather than vscode-java waiting to start by using the activation events defined in the plugin. My thoughts are that if activation events were working the java language server would not start eagerly. Then we can trigger the cloning of all projects and then update the workspace root. Then and only then, the language server initialization would start (because the activation events would be triggered), rather than it starting eagerly like it does now. If all the projects are cloned before the server is started then the workspaceFolders in initialialization will be sent correctly to the server and then all will proceed as expected. Additionally, if any projects are cloned after this, the client would then send a workspace/updateWorkspaceFolders event and the language server will handle the new folder. I believe this should resolve the race condition.

Just from quickly inspecting a few of the vscode language plugins supported in Che, it seems like they have reasonable activation events such as activating when a language (such as python) is selected, or activating on command, workspace contains etc.

I’d like to know what other peoples opinions are on this.

[1] - https://github.com/JPinkney/che-theia/commits/workspace_roots_che