[feature] Add support for passing customization to XML language server and extensions (didChangeConfiguration)

When starting XML language server it would be nice if the language server launcher can inject some system properties from the host JVM to language server JVM

Why? XML extensions such as lemminx-maven depends on several configuration parameters such as the global maven config, user config, and local repository path. Since the extensions can’t directly depend on the host IDE for these settings, the above mechanism can be used inside eclipse to pass in the required m2e configuration as JVM properties.

How? The XML language server launcher can introduce a JVM property namespace like lemminx. . lemminx-maven can define system properties like lemminx.m2.global.config, lemminx.m2.repo for example. All these properties under the lemminx. namespace are injected into the XML language server JVM by the XML language server launcher.

@angelozerr @mickaelistria I would like to hear your thoughts about this proposal.

[angelozerr]

Is this what you have in mind?

Exactly and LemMinx support already that. All extensions reacts from settings on startup and when settings changed (it works pretty well on vscode).

For extension side, you need to implement doSave like https://github.com/eclipse/lemminx/blob/f12cf5d1cbd47f59bdb4b632bed57b11b8195be2/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/ContentModelPlugin.java#L92

[mickaelistria]

OK, I get it better. This is indeed something to consider, instead of using system properties at startup, send some didChangeConfiguration. Is this what you have in mind?