diff --git a/src/main/java/com/puppycrawl/tools/checkstyle/gui/AbstractCellEditor.java b/src/main/java/com/puppycrawl/tools/checkstyle/gui/AbstractCellEditor.java
index 42422d248..f160a5e55 100644
--- a/src/main/java/com/puppycrawl/tools/checkstyle/gui/AbstractCellEditor.java
+++ b/src/main/java/com/puppycrawl/tools/checkstyle/gui/AbstractCellEditor.java
@@ -21,23 +21,23 @@
  * %W% %E%
  *
  * Copyright 1997, 1998 Sun Microsystems, Inc. All Rights Reserved.
- * 
+ *
  * Redistribution and use in source and binary forms, with or
  * without modification, are permitted provided that the following
  * conditions are met:
- * 
+ *
  * - Redistributions of source code must retain the above copyright
- *   notice, this list of conditions and the following disclaimer. 
- *   
+ *   notice, this list of conditions and the following disclaimer.
+ *
  * - Redistribution in binary form must reproduce the above
  *   copyright notice, this list of conditions and the following
  *   disclaimer in the documentation and/or other materials
- *   provided with the distribution. 
- *   
+ *   provided with the distribution.
+ *
  * Neither the name of Sun Microsystems, Inc. or the names of
  * contributors may be used to endorse or promote products derived
- * from this software without specific prior written permission.  
- * 
+ * from this software without specific prior written permission.
+ *
  * This software is provided "AS IS," without a warranty of any
  * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
  * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
@@ -45,13 +45,13 @@
  * EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY
  * DAMAGES OR LIABILITIES SUFFERED BY LICENSEE AS A RESULT OF OR
  * RELATING TO USE, MODIFICATION OR DISTRIBUTION OF THIS SOFTWARE OR
- * ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE 
- * FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT,   
- * SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER  
- * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF 
- * THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS 
+ * ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE
+ * FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT,
+ * SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
+ * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF
+ * THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS
  * BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
- * 
+ *
  * You acknowledge that this software is not designed, licensed or
  * intended for use in the design, construction, operation or
  * maintenance of any nuclear facility.
@@ -66,14 +66,14 @@ import javax.swing.event.CellEditorListener;
 import javax.swing.event.ChangeEvent;
 import javax.swing.event.EventListenerList;
 
-/** 
- * A base class for CellEditors, providing default implementations for all 
- * methods in the CellEditor interface and support for managing a series 
+/**
+ * A base class for CellEditors, providing default implementations for all
+ * methods in the CellEditor interface and support for managing a series
  * of listeners.
  *
  * <a href="https://docs.oracle.com/cd/E48246_01/apirefs.1111/e13403/oracle/ide/controls/TreeTableModel.html">
  * Original&nbsp;Source&nbsp;Location</a>
- * 
+ *
  * @author Philip Milne
  */
 public class AbstractCellEditor implements CellEditor {
diff --git a/src/main/java/com/puppycrawl/tools/checkstyle/gui/TreeTableModel.java b/src/main/java/com/puppycrawl/tools/checkstyle/gui/TreeTableModel.java
index 82ece3e77..b3f3fab60 100644
--- a/src/main/java/com/puppycrawl/tools/checkstyle/gui/TreeTableModel.java
+++ b/src/main/java/com/puppycrawl/tools/checkstyle/gui/TreeTableModel.java
@@ -2,23 +2,23 @@
  * %W% %E%
  *
  * Copyright 1997, 1998 Sun Microsystems, Inc. All Rights Reserved.
- * 
+ *
  * Redistribution and use in source and binary forms, with or
  * without modification, are permitted provided that the following
  * conditions are met:
- * 
+ *
  * - Redistributions of source code must retain the above copyright
- *   notice, this list of conditions and the following disclaimer. 
- *   
+ *   notice, this list of conditions and the following disclaimer.
+ *
  * - Redistribution in binary form must reproduce the above
  *   copyright notice, this list of conditions and the following
  *   disclaimer in the documentation and/or other materials
- *   provided with the distribution. 
- *   
+ *   provided with the distribution.
+ *
  * Neither the name of Sun Microsystems, Inc. or the names of
  * contributors may be used to endorse or promote products derived
- * from this software without specific prior written permission.  
- * 
+ * from this software without specific prior written permission.
+ *
  * This software is provided "AS IS," without a warranty of any
  * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
  * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
@@ -26,13 +26,13 @@
  * EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY
  * DAMAGES OR LIABILITIES SUFFERED BY LICENSEE AS A RESULT OF OR
  * RELATING TO USE, MODIFICATION OR DISTRIBUTION OF THIS SOFTWARE OR
- * ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE 
- * FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT,   
- * SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER  
- * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF 
- * THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS 
+ * ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE
+ * FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT,
+ * SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
+ * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF
+ * THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS
  * BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
- * 
+ *
  * You acknowledge that this software is not designed, licensed or
  * intended for use in the design, construction, operation or
  * maintenance of any nuclear facility.
@@ -44,15 +44,15 @@ import javax.swing.tree.TreeModel;
 
 /**
  * TreeTableModel is the model used by a JTreeTable. It extends TreeModel
- * to add methods for getting information about the set of columns each 
- * node in the TreeTableModel may have. Each column, like a column in 
- * a TableModel, has a name and a type associated with it. Each node in 
- * the TreeTableModel can return a value for each of the columns and 
- * set that value if isCellEditable() returns true. 
+ * to add methods for getting information about the set of columns each
+ * node in the TreeTableModel may have. Each column, like a column in
+ * a TableModel, has a name and a type associated with it. Each node in
+ * the TreeTableModel can return a value for each of the columns and
+ * set that value if isCellEditable() returns true.
  *
  * <a href="http://java.sun.com/products/jfc/tsc/articles/treetable1/index.html">Original&nbsp;Source&nbsp;Location</a>
  *
- * @author Philip Milne 
+ * @author Philip Milne
  * @author Scott Violet
  */
 public interface TreeTableModel extends TreeModel {
@@ -76,25 +76,25 @@ public interface TreeTableModel extends TreeModel {
     /**
      * @param node the node
      * @param column the column number
-     * @return the value to be displayed for node <code>node</code>, 
+     * @return the value to be displayed for node <code>node</code>,
      * at column number <code>column</code>.
      */
     Object getValueAt(Object node, int column);
 
     /**
-     * Indicates whether the the value for node <code>node</code>, 
+     * Indicates whether the the value for node <code>node</code>,
      * at column number <code>column</code> is editable.
-     * 
+     *
      * @param node the node.
      * @param column the column number
-     * @return true if editable 
+     * @return true if editable
      */
     boolean isCellEditable(Object node, int column);
 
     /**
-     * Sets the value for node <code>node</code>, 
+     * Sets the value for node <code>node</code>,
      * at column number <code>column</code>.
-     * 
+     *
      * @param aValue the value to set
      * @param node the node to set the value on
      * @param column the column number