XMLHover.getTextHover() shouldn't log CancellationExceptions

[fbricon]

I tried using the lemminx-maven jars with vscode-xml, and saw this exception in the output view:

[Error - 09:50:29] Nov 10, 2023 09:50:29 org.eclipse.lemminx.services.XMLHover getTextHover()
Message: While performing IHoverParticipant#onText
java.util.concurrent.CancellationException
	at org.eclipse.lsp4j.jsonrpc.CompletableFutures$FutureCancelChecker.checkCanceled(CompletableFutures.java:59)
	at org.eclipse.lemminx.extensions.maven.participants.hover.MavenHoverParticipant.collectArtifactDescription(MavenHoverParticipant.java:381)
	at org.eclipse.lemminx.extensions.maven.participants.hover.MavenHoverParticipant.onText(MavenHoverParticipant.java:153)
	at org.eclipse.lemminx.services.XMLHover.getTextHover(XMLHover.java:214)
	at org.eclipse.lemminx.services.XMLHover.doHover(XMLHover.java:99)
	at org.eclipse.lemminx.services.XMLLanguageService.doHover(XMLLanguageService.java:185)
	at org.eclipse.lemminx.XMLTextDocumentService.lambda$hover$5(XMLTextDocumentService.java:281)
	at org.eclipse.lemminx.commons.ModelTextDocuments.lambda$computeModelAsync$0(ModelTextDocuments.java:118)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:646)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:483)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:373)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1182)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1655)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1622)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:165)

https://github.com/eclipse/lemminx/blob/d1d67ec09ad8ded638fc7c8ce1f52b72b33b8ec9/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/services/XMLHover.java#L219 should probably re-throw CancellationException and let the client handle the cancelled request

[angelozerr]

We did that for other LSP opertaion like completion https://github.com/eclipse/lemminx/blob/d1d67ec09ad8ded638fc7c8ce1f52b72b33b8ec9/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/services/XMLCompletions.java#L334

The main problem with this strategy is that if one participant throws a cancelled exception it breaks other particpant result. Ex : if lemminx provides hover for XSD documentation and lemminx-maven throws a cancelled exception because some maven component are not loaded, the XSD documentation will not displayed.

Cancelled exception can occur in 2 usecase:

• the DOMDocument has changed, so we should stop all participant process
• one participant throws a cancelled exception (like lemminx maven) and we should not stop the hover process.

We need to take care of those 2 usecases.