Maven preference settings not available initially when the application starts with the preference page opened

[lmcbout]

Description

Starting a maven project when the preference editor is open does not show the maven sub-folder

Reproduction Steps

Tested on Electron.

Open a maven project
Open the preference settings page
Close the backend application (File->Close workspace)
Restart the electron application (Open the workspace)
--> should open with the latest workspace and the preference settings page open in the editor
--> Look to find the tab for the maven settings, not there
Close the preference settings page
Re-open the preference setting page (File-> Settings-> Open Preference)
--> The maven tab settings is available

OS and Theia version:
Electron on Ubuntu 16.04
Theia: master

Configuration: package.json: remove @theia/java
Plugins installed:
    redhat.java-051.0.vsix
    vscjava.vscode-java-debug-0.22.0.vsix
    vscode-java-dependency-0.6.0.vsix
    vscode-java-test-0.20.0.vsix
    vscjava.vscode-maven-0.19.1.vsix

Diagnostics:

[lmcbout]

Tested with the pr #6510 and it will solved this issue when merged.

[vzhukovs]

PR #6510 has been merged to the master. @lmcbout, recheck the new changes

[lmcbout]

Tested with the next version of Theia and the problem is solved
This issue will be fixed and merged in the next official release of Theia end of November
@vzhukovskii Thanks,

[vzhukovs]

@lmcbout you're welcome