Match diagnostics with empty ranges

In Eclipse, we set a minimal range of 1 character, even for diagnostics
that have an empty range (just a position); so this fixes ensure such
markers and diagnostics are still matched together upon update, to avoid
re-creating diagnostics.

org.eclipse.lsp4e.tests.mock/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: Mock Language Server to test LSP4E
 Bundle-SymbolicName: org.eclipse.lsp4e.tests.mock
-Bundle-Version: 0.16.1.qualifier
+Bundle-Version: 0.16.2.qualifier
 Bundle-Vendor: Eclipse LSP4E
 Bundle-RequiredExecutionEnvironment: JavaSE-17
 Require-Bundle: org.eclipse.lsp4j;bundle-version="[0.20.0,0.21.0)",

org.eclipse.lsp4e.tests.mock/src/org/eclipse/lsp4e/tests/mock/MockTextDocumentService.java

@@ -238,10 +238,17 @@ public void didOpen(DidOpenTextDocumentParams params) {
 		}
 
 		if (this.diagnostics != null && !this.diagnostics.isEmpty()) {
-			// 'collect(Collectors.toSet()` is added here in order to prevent a
-			// ConcurrentModificationException appearance
-			this.remoteProxies.stream().collect(Collectors.toSet()).forEach(p -> p.publishDiagnostics(
-					new PublishDiagnosticsParams(params.getTextDocument().getUri(), this.diagnostics)));
+			// we're not sure which remote proxy to use, but we know we should only use one
+			// per didOpen
+			// for proper LS interaction; so a strategy is to use the first one and rotate
+			// the others
+			// for further executions
+			synchronized (this.remoteProxies) {
+				// and we synchronize to avoid concurrent read/write on the list
+				this.remoteProxies.get(0).publishDiagnostics(
+						new PublishDiagnosticsParams(params.getTextDocument().getUri(), this.diagnostics));
+				Collections.rotate(this.remoteProxies, 1);
+			}
 		}
 	}
 

org.eclipse.lsp4e/src/org/eclipse/lsp4e/operations/diagnostics/LSPDiagnosticsToMarkers.java

@@ -207,7 +207,7 @@ private IMarker getExistingMarkerFor(IDocument document, Diagnostic diagnostic,
 		for (IMarker marker : remainingMarkers) {
 			try {
 				if (LSPEclipseUtils.toOffset(diagnostic.getRange().getStart(), document) == MarkerUtilities.getCharStart(marker)
-						&& LSPEclipseUtils.toOffset(diagnostic.getRange().getEnd(), document) == MarkerUtilities.getCharEnd(marker)
+						&& (LSPEclipseUtils.toOffset(diagnostic.getRange().getEnd(), document) == MarkerUtilities.getCharEnd(marker) || Objects.equals(diagnostic.getRange().getStart(), diagnostic.getRange().getEnd()))
 						&& Objects.equals(marker.getAttribute(IMarker.MESSAGE), diagnostic.getMessage())
 						&& Objects.equals(marker.getAttribute(LANGUAGE_SERVER_ID), this.languageServerId)) {
 					return marker;