testing: Mitigate flaky test

I think there were always potentially multiple annotations at the expected location, and depending on luck would get the one we were expecting first.
No idea why the totally unrelated change to WorkspaceFoldersTest in the preceding commit made this test fail 100% of the time (even when run in isolation),
but it did!

org.eclipse.lsp4e.test/src/org/eclipse/lsp4e/test/linkedediting/LinkedEditingTest.java

@@ -141,13 +141,12 @@ protected boolean condition() {
 		}.waitForCondition(Display.getCurrent(), 3000);
 
 		IAnnotationModel model = sourceViewer.getAnnotationModel();
-		Annotation annotation = findAnnotation(sourceViewer, 14);
-		Assert.assertNotNull(annotation);
-//		System.out.println("testLinkedEditingExitPolicy: annotation found at offset 14: " + annotation.getType());
-		assertTrue(annotation.getType().startsWith("org.eclipse.ui.internal.workbench.texteditor.link"));
+		List<Annotation> annotations = findAnnotations(sourceViewer, 14);
+		Assert.assertFalse(annotations.isEmpty());
+		assertTrue(annotations.stream().anyMatch(a -> a.getType().startsWith("org.eclipse.ui.internal.workbench.texteditor.link")));
 		Annotation masterAnnotation = findAnnotation(sourceViewer, "org.eclipse.ui.internal.workbench.texteditor.link.master");
 		assertNotNull(masterAnnotation);
-		assertEquals(annotation, masterAnnotation);
+		assertTrue(annotations.contains(masterAnnotation));
 		org.eclipse.jface.text.Position masterPosition = model.getPosition(masterAnnotation);
 		assertNotNull(masterPosition);
 		Annotation slaveAnnotation = findAnnotation(sourceViewer, "org.eclipse.ui.internal.workbench.texteditor.link.slave");
@@ -167,7 +166,6 @@ protected boolean condition() {
 				while (iterator.hasNext()) {
 					Annotation annotation = iterator.next();
 					if (annotation.getType().startsWith("org.eclipse.ui.internal.workbench.texteditor.link")) {
-//						System.out.println("testLinkedEditingExitPolicy: Wait for annotation succeeded: " + annotation.getType());
 						return true;
 					}
 				}
@@ -176,26 +174,26 @@ protected boolean condition() {
 		}.waitForCondition(Display.getCurrent(), 3000);
 
 		model = sourceViewer.getAnnotationModel();
-		annotation = findAnnotation(sourceViewer, 15);
+		annotations = findAnnotations(sourceViewer, 15);
 		// No "linked" annotation is to be found at this offset
-		if (annotation != null) {
-//			System.out.println("testLinkedEditingExitPolicy: annotation found at offset 15: " + annotation.getType());
-			assertFalse(annotation.getType().startsWith("org.eclipse.ui.internal.workbench.texteditor.link"));
+		if (!annotations.isEmpty()) {
+			assertFalse(annotations.stream().anyMatch(a -> a.getType().startsWith("org.eclipse.ui.internal.workbench.texteditor.link")));
 		}
 	}
 
-	private Annotation findAnnotation(ISourceViewer sourceViewer, int offset) {
+	private List<Annotation> findAnnotations(ISourceViewer sourceViewer, int offset) {
+		List<Annotation> annotations = new ArrayList<>();
 		IAnnotationModel model = sourceViewer.getAnnotationModel();
 		Iterator<Annotation> iterator = model.getAnnotationIterator();
 		while (iterator.hasNext()) {
 			Annotation annotation = iterator.next();
 			org.eclipse.jface.text.Position position = model.getPosition(annotation);
 			if (position != null && position.includes(offset)) {
-				return annotation;
+				annotations.add(annotation);
 			}
 		}
 
-		return null;
+		return annotations;
 	}
 
 	private Annotation findAnnotation(ISourceViewer sourceViewer, String type) {