FieldGroup should not throw NPE when data source is not set (#14901).

Change-Id: I74bea857306fac5123aa86cdabc70d81c2a72094

server/src/com/vaadin/data/fieldgroup/FieldGroup.java

@@ -211,7 +211,8 @@ public class FieldGroup implements Serializable {
     public void setReadOnly(boolean fieldsReadOnly) {
         readOnly = fieldsReadOnly;
         for (Field<?> field : getFields()) {
-            if (!field.getPropertyDataSource().isReadOnly()) {
+            if (field.getPropertyDataSource() == null
+                    || !field.getPropertyDataSource().isReadOnly()) {
                 field.setReadOnly(fieldsReadOnly);
             } else {
                 field.setReadOnly(true);

server/tests/src/com/vaadin/tests/server/component/fieldgroup/FieldGroupTest.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2000-2014 Vaadin Ltd.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.tests.server.component.fieldgroup;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.vaadin.data.fieldgroup.FieldGroup;
+import com.vaadin.ui.TextField;
+
+/**
+ * 
+ * Tests for {@link FieldGroup}.
+ * 
+ * @author Vaadin Ltd
+ */
+public class FieldGroupTest {
+
+    @Test
+    public void setReadOnly_readOnlyAndNoDataSource_fieldIsReadOnly() {
+        FieldGroup fieldGroup = new FieldGroup();
+
+        TextField field = new TextField();
+        fieldGroup.bind(field, "property");
+
+        fieldGroup.setReadOnly(true);
+
+        Assert.assertTrue("Field is not read only", field.isReadOnly());
+    }
+
+    @Test
+    public void setReadOnly_writableAndNoDataSource_fieldIsWritable() {
+        FieldGroup fieldGroup = new FieldGroup();
+
+        TextField field = new TextField();
+        fieldGroup.bind(field, "property");
+
+        fieldGroup.setReadOnly(false);
+
+        Assert.assertFalse("Field is not writable", field.isReadOnly());
+    }
+}