Added escaped character replacement.

Author: MIchaelMainer

src/GraphODataTemplateWriter/CodeHelpers/TypeScript/TypeHelperTypeScript.cs

@@ -62,7 +62,12 @@ public static String UpperCaseFirstChar(this String s)
 
         public static string GetSanitizedLongDescription(this OdcmProperty property)
         {
-            return property.LongDescription ?? property.Description;
+            var description = property.LongDescription ?? property.Description;
+            if (description != null)
+            {
+                return description.Replace("<", "&lt;").Replace(">", "&gt;").Replace("&", "&amp;");
+            }
+            return null;
         }
     }
 }