Fixes: U4-2627 Ensure that the plugins cache files are named with the machine name

src/Umbraco.Core/StringExtensions.cs

@@ -28,6 +28,17 @@ namespace Umbraco.Core
         [UmbracoWillObsolete("Do not use this constants. See IShortStringHelper.CleanStringForSafeAliasJavaScriptCode.")]
         public const string UmbracoInvalidFirstCharacters = "01234567890";
 
+        internal static string ReplaceNonAlphanumericChars(this string input, char replacement)
+        {
+            //any character that is not alphanumeric, convert to a hyphen
+            var mName = input;
+            foreach (var c in mName.ToCharArray().Where(c => !char.IsLetterOrDigit(c)))
+            {
+                mName = mName.Replace(c, replacement);
+            }
+            return mName;
+        }
+
         public static string ExceptChars(this string str, HashSet<char> toExclude)
         {
             var sb = new StringBuilder(str.Length);