Add tabindex to grid columns which has only plain text to make it tabable

Signed-off-by: Pasam Soujanya <psoujany@in.ibm.com>

Author: psoujany

src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/Table.java

@@ -22,6 +22,11 @@
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
+/*
+ * ===========================================================================
+ * (c) Copyright IBM Corp. 2025, 2025 All Rights Reserved
+ * ===========================================================================
+ */
 
 package jdk.javadoc.internal.doclets.formats.html;
 
@@ -33,6 +38,7 @@
 import java.util.List;
 import java.util.Set;
 import java.util.function.Predicate;
+import java.util.regex.Pattern;
 
 import jdk.javadoc.internal.doclets.formats.html.markup.HtmlStyles;
 import jdk.javadoc.internal.html.Content;
@@ -322,14 +328,25 @@ public void addRow(T item, List<Content> contents) {
             }
         }
         int colIndex = 0;
+        String regex = "<(?:a|area|button|input|object|select|textarea)\\b";
+        Pattern pattern = Pattern.compile(regex);
         for (Content c : contents) {
             HtmlStyle cellStyle = columnStyles.get(colIndex);
             // Always add content to make sure the cell isn't dropped
             var cell = HtmlTree.DIV(cellStyle).addUnchecked(c.isEmpty() ? Text.EMPTY : c);
+            boolean matchFound = c.isEmpty() || pattern.matcher(c.toString()).find();
             cell.addStyle(rowStyle);
+            if (!matchFound) {
+                cell.put(HtmlAttr.ROLE, "tablist")
+                    .put(HtmlAttr.TABINDEX, "0");
+            }
 
             for (String tabClass : tabClasses) {
                 cell.addStyle(tabClass);
+                if (!matchFound) {
+                    cell.put(HtmlAttr.ROLE, "tablist")
+                        .put(HtmlAttr.TABINDEX, "0");
+                }
             }
             row.add(cell);
             colIndex++;