FULL PRODUCT VERSION :
java version "1.7.0_65"
Java(TM) SE Runtime Environment (build 1.7.0_65-b17)
Java HotSpot(TM) 64-Bit Server VM (build 24.65-b04, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Darwin cthulhu.local 13.3.0 Darwin Kernel Version 13.3.0: Tue Jun 3 21:27:35 PDT 2014; root:xnu-2422.110.17~1/RELEASE_X86_64 x86_64

A DESCRIPTION OF THE PROBLEM :
I have an HTMLDocument.
I append lines, one after the other, into it.
A line that starts with a "/" character is suppressed, up to the first tag.
For example, the following:

Test1.insertHTML( doc, "Line 1<br>" );
Test1.insertHTML( doc, "Line 2/<br>" );
Test1.insertHTML( doc, "/Line 3<br>" );
Test1.insertHTML( doc, "Line/ 4<br>" );

results in the following:

Line1<br>Line2/<br><br>Line/ 4<br>

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
bash-3.2$ setjdk 1.7.0_65
bash-3.2$ java -version
java version "1.7.0_65"
Java(TM) SE Runtime Environment (build 1.7.0_65-b17)
Java HotSpot(TM) 64-Bit Server VM (build 24.65-b04, mixed mode)
bash-3.2$ javac Test1.java
bash-3.2$ java Test1

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I expect a Frame to pop up containing 4 lines with the specified text.
ACTUAL -
A Frame pops up with 4 lines, but the line that started with a / is blank.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.io.StringWriter;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.Element;
import javax.swing.text.html.HTMLDocument;
import javax.swing.text.html.HTMLEditorKit;

public abstract class Test1
{
private static void insertHTML( final HTMLDocument doc, final String text )
        {
Element contentElement = doc.getDefaultRootElement();
while ( !contentElement.isLeaf() ) {
contentElement = contentElement.getElement( contentElement.getElementCount() - 1 );
}

try
{
doc.insertAfterEnd( contentElement, text );
}
catch ( Exception e )
{
}
}

private static void printHTML( final HTMLDocument doc )
        {
HTMLEditorKit kit = new HTMLEditorKit();
StringWriter writer = new StringWriter();
try
{
kit.write(writer, doc, 0, doc.getLength());
}
catch ( Exception e )
{
}
String s = writer.toString();
System.out.println( "New HTML = \"" + s + "\"" );
}

private static void createAndShowGUI()
        {
// Create and set up the window.

JFrame frame = new JFrame();
frame.setTitle( "Test1 HTML Frame" );
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );

Container contents = frame.getContentPane();

JEditorPane pane = new JEditorPane();
pane.setContentType( "text/html" );
pane.setEditable( false );

HTMLDocument doc = (HTMLDocument) pane.getDocument();
Test1.insertHTML( doc, "Line 1<br>" );
Test1.insertHTML( doc, "Line 2/<br>" );
Test1.insertHTML( doc, "/Line 3<br>" );
Test1.insertHTML( doc, "Line/ 4<br>" );
// Test1.printHTML( doc );

contents.add( pane, BorderLayout.CENTER );

//Display the window.
frame.pack();
frame.setVisible(true);
}

/**
* The main method.
*/

public static final void main( final String[] args )
{
javax.swing.SwingUtilities.invokeLater(
new Runnable() {
public void run() {
createAndShowGUI();
}
} );

while (true ) {
try
{
Thread.sleep( 1000 );
}
catch ( InterruptedException e )
{
break;
}
}
}
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
I can wrap the text in <span></span>