Handling Java inter-projects dependencies in multi-root workspace

I'm testing Theia as an Eclipse replacement IDE for my Java projects and am trying to replicate the familiar project structure: a workspace directory containing a folder per project, each project depends on external jars and other projects. E.g.

• prjA depends on some.jar (copied into the lib subdirectory)
• prjB depends on other.jar and on prjA

Even though Theia is not a fork of VSCode, its structure is heavily influenced by it (for extensions compatibility I guess?) but I was unable to find anything for VSCode too.

I have been able to create my two Java projects, each with .vscode/settings.json (and also .theia/settings.jsons, which I put to the same content):

• prjA/.vscode/settings.json:

{
    "java.project.sourcePaths": ["src"],
    "java.project.outputPath": ".bin",
    "java.project.referencedLibraries": [
        "lib/**/*.jar"
    ]
}

• prjB/.vscode/settings.json:

{
    "java.project.sourcePaths": ["src"],
    "java.project.outputPath": ".bin",
    "java.project.referencedLibraries": [
        "lib/**/*.jar",
        "../prjA/.bin"
    ]
}

(note the added "../prjA/.bin" in prjB).

Yet, I cannot have intellisense detecting the classpath correctly in prjB: classes from external jars are properly identified, but the ones from prjA still show with red waves with The import xxx cannot be resolved.

I tried adding ../prjA/src as an additionnal sourcePaths (through a link because it won't let me add a source folder not in its root), but it compiles prjA's classes into prjB/.bin, which I obviously don't want (but the "import cannot be resolved" errors disappear though).

So, how should I approach Java projects dependencies in a multi-root workspace? (Preferably for Theia, but curious about VSCode as well).