Fix ability to disable "no grammar" message

Fixes redhat-developer/vscode-xml#467

Signed-off-by: David Thompson <[email protected]>

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/extensions/contentmodel/settings/XMLValidationSettings.java

@@ -182,6 +182,7 @@ public XMLValidationSettings merge(XMLValidationSettings settings) {
 			this.namespaces = settings.namespaces;
 			this.schema = settings.schema;
 			this.enabled = settings.enabled;
+			this.noGrammar = settings.noGrammar;
 			this.disallowDocTypeDecl = settings.disallowDocTypeDecl;
 			this.resolveExternalEntities = settings.resolveExternalEntities;
 		}

org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/settings/SettingsMergeTest.java

@@ -0,0 +1,38 @@
+/*******************************************************************************
+* Copyright (c) 2021 Red Hat Inc. and others.
+* All rights reserved. This program and the accompanying materials
+* which accompanies this distribution, and is available at
+* http://www.eclipse.org/legal/epl-v20.html
+*
+* Contributors:
+*     Red Hat Inc. - initial API and implementation
+*******************************************************************************/
+package org.eclipse.lemminx.settings;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+import java.lang.reflect.Field;
+
+import org.eclipse.lemminx.extensions.contentmodel.settings.XMLValidationSettings;
+import org.eclipse.lsp4j.PublishDiagnosticsCapabilities;
+import org.junit.jupiter.api.Test;
+
+public class SettingsMergeTest {
+
+	@Test
+	public void testValidationSettingsMerge() throws IllegalArgumentException, IllegalAccessException {
+		XMLValidationSettings settings = new XMLValidationSettings();
+		settings.setEnabled(false);
+		settings.setDisallowDocTypeDecl(true);
+		settings.setNoGrammar("ignore");
+		settings.setResolveExternalEntities(true);
+		settings.setCapabilities(new PublishDiagnosticsCapabilities());
+		settings.setNamespaces(null);
+		settings.setSchema(null);
+		XMLValidationSettings mergeTargetSettings = new XMLValidationSettings();
+		mergeTargetSettings.merge(settings);
+		assertEquals(settings, mergeTargetSettings);
+	}
+
+}