Java Overview will break the import of invisible project #1198

When opening a folder containing an invisible project, if Java Overview pops up, the project will fail to be imported, because initializationOptions does not contain a trigger file:

Collection<IPath> triggerFiles = preferencesManager.getPreferences().getTriggerFiles();
if (triggerFiles == null || triggerFiles.isEmpty()) {
    return;
}

from https://github.com/eclipse/eclipse.jdt.ls/blob/master/org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/managers/InvisibleProjectImporter.java#L72-L75

It is root-caused in getTriggerFiles, where it only retrives text editors. When Java Overview pops up, the triggered file actually goes to background, and cannot be retrieved in window.visibleTextEditors.

Environment

• Operating System: Windows 10
• Java version: openjdk 1.8
• Visual Studio Code Version: 1.40.2
• Java extension version: master branch

Reproduce steps

1. Make sure Show overview page when using Java is set
2. Open a folder containing an invisible project.

Sample project: https://github.com/santiontanon/microrts

Current Result

"Classpath is incomplete. Only syntax error is reported."

Expected Result

Project should successfully build.