javadoc @links to other -linked packages but still not to 
(all) contained classes (or further down methods and fields);
see below. 

If you javadoc the example already known

------------- start ------------------------
package DE.a_weinert.math;
import  DE.a_weinert.math.DecDigsIntf;

/** <b>Dezimalzahl, ziffernweise</b>. <br />
 *  <br />
 *  Objekte dieser Klasse stellen eine Dezimalzahl 
 *  blah blah ......................
 *  @author   Albrecht Weinert
 *  @version  V00.02 (11.03.2002 09:17)
 *  @see DE.a_weinert.math
 *  @see DE.a_weinert.math.Complex
 *  @see DE.a_weinert.math.CFun
 *  @see DE.a_weinert.math.SFun
 *  @see DE.a_weinert.math.DecDigsIntf
 *  @see DE.a_weinert.math.DecFormat
 */
 // bisher    V00.00 (27.10.2000 10:35) : Anfang
 //           V00.01 (03.11.2000 18:36) : Parsen nach DecDigsP
 //           V00.02 (11.03.2002 08:57) : /**
 //  
public class DecDigs implements DecDigsIntf {

//....  much code 

/** Setzen mit double. <br />
 *  <br />
 *  Diese Methode ist schneller aber etwas ungenauer (etwa auf 16
Stellen) als
 *  entsprechende Methoden beziehungsweise Konstruktoren von 
 *  {@link java.lang.Double} beziehungsweise 
 *  {@link java.math.BigDecimal}.
 *  Entsprechend schlie��t sie einen Aufruf von 
 *  {@link #roundTo roundTo}(16) 
 *  oder f��r gro��e negative Exponenten von 
 *  {@link #roundTo roundTo}(15) ein.
 */
   public void set(double d) {
// ...... and the rest

------------- End ------------------------

and all the packages with the commands  

------------- start ------------------------ 

if not exist C:\Programme\jdk\docs\aWeinertBib\nul 
     md C:\Programme\jdk\docs\aWeinertBib

PushD C:\Programme\jdk\docs\aWeinertBib

C:\Programme\jdk\docs\aWeinertBib>  if exist 
       ..\api\org\w3c\dom\Document.html goto :m1-1.4
REM Seit 1.4.x haben wir endlich XML.

C:\Programme\jdk\docs\aWeinertBib>  Javadoc -author -version 
  -protected -use -J-mx 32m -J-ms32m -link ../api -link ../jDOM   
-sourcepath D:\Weinert\javaFactory  @D:\Weinert\javaFactory\DEawDoc.list

Loading source file D:\Weinert\javaFactory\FS.java...
Loading source file D:\Weinert\javaFactory\FuR.java...
Loading source file D:\Weinert\javaFactory\KnopfGen.java...

------------- End ------------------------

you get one warning :

----------  start-----------------------------
Generating DE\a_weinert\math\DecDigs.html...
D:\Weinert\javaFactory\DE\a_weinert\math\DecDigs.java:409: warning - Tag
@link:
reference not found: java.math.BigDecimal
-----------------  end -------------------------

and the .html

----------  start-----------------------------
 <A HREF="../../../../api/java/lang/Double.html"><CODE>Double</CODE></A>
beziehungsweise 
  <CODE>java.math.BigDecimal</CODE>.
-----------------  end -------------------------

Now:

If you change

 *  {@link java.lang.Double} beziehungsweise 
 *  {@link java.math.BigDecimal}.

to the mystirious }} 

 *  {@link java.lang.Double} beziehungsweise 
 *  {@link java.math}.BigDecimal}.

you get no warnings at all 
and the .html

----------  start-----------------------------
  <A
HREF="../../../../api/java/lang/Double.html"><CODE>Double</CODE></A>
beziehungsweise 
  <A
HREF="../../../../api/java/math/package-summary.html">java.math</A>.BigDecimal}.
-----------------  end -------------------------


So, from all the stuff below, the javadoc bug that survived bta to 
final is:

javadoc can @link to -linked standard packages but not to 
(all ?!?) classes (or further down methods and fields) in them. 

That is much to my (our?) surprise as the javadoc description
promises to look only in the package lists and generate the links 
to inside blindly. So the link to BigDecimal should have been
generated (even if BigDecimal wouldn't exist, which, of course, it
does) like the link to Double.

As we see, the link to Double is done now. The beta javadoc 
failed there as well.

So, now, thats your turn.