Fix checking if cell is locked

OpenXmlFormats/Spreadsheet/Styles/CT_CellProtection.cs

@@ -30,7 +30,7 @@ public static CT_CellProtection Parse(XmlNode node, XmlNamespaceManager namespac
             if (node == null)
                 return null;
             CT_CellProtection ctObj = new CT_CellProtection();
-            ctObj.locked = XmlHelper.ReadBool(node.Attributes["locked"]);
+            ctObj.locked = XmlHelper.ReadBool(node.Attributes["locked"], true);
             ctObj.hidden = XmlHelper.ReadBool(node.Attributes["hidden"]);
             return ctObj;
         }

ooxml/XSSF/UserModel/XSSFCellStyle.cs

@@ -806,7 +806,6 @@ public bool IsLocked
         {
             get
             {
-
                 if (!_cellXf.IsSetProtection())
                 {
                     return true;

testcases/ooxml/XSSF/UserModel/TestXSSFCellStyle.cs

@@ -724,9 +724,24 @@ public void TestGetSetLocked()
             cellStyle.IsLocked = (false);
             Assert.IsFalse(cellStyle.IsLocked);
         }
+        [Test]
+        public void TestBug738()
+        {
+            XSSFWorkbook wb = XSSFTestDataSamples.OpenSampleWorkbook("738.xlsx");
+
+            ISheet sheet = wb.GetSheet("Sheet1");
+            IRow row = sheet.GetRow(0);
+            ICell cell = row.GetCell(0);
+            Assert.IsTrue(cell.CellStyle.IsLocked);
+            cell.CellStyle.IsLocked = true;
+            Assert.IsTrue(cell.CellStyle.IsLocked);
+            Assert.IsTrue(cell.CellStyle.IsHidden);
+        }
+
         [Test]
         public void TestGetSetIndent()
         {
+
             Assert.AreEqual((short)0, cellStyle.Indention);
             cellStyle.Indention = ((short)3);
             Assert.AreEqual((short)3, cellStyle.Indention);