Address a comment

Author: wschin

src/Microsoft.ML.Transforms/Text/WordTokenizing.cs

@@ -105,7 +105,7 @@ private static VersionInfo GetVersionInfo()
 
         private const string RegistrationName = "DelimitedTokenize";
 
-        public IReadOnlyCollection<WordTokenizingEstimator.ColumnOptions> Columns => _columns.AsReadOnly();
+        internal IReadOnlyCollection<WordTokenizingEstimator.ColumnOptions> Columns => _columns.AsReadOnly();
         private readonly WordTokenizingEstimator.ColumnOptions[] _columns;
 
         private static (string name, string inputColumnName)[] GetColumnPairs(WordTokenizingEstimator.ColumnOptions[] columns)