gdcm packaging: covariant return type / default-jdk

[Mathieu Malaterre <mathieu.malaterre@gmail.com>]

Hello there java-packagers gurus,

  I am trying to wrap the gdcm API in java using SWIG. Everything
seems to be going on well in my pbuilder/amd64 environment, but
someone else tried on a pbuilder/i386 environment and is getting the
following error:

...
[ 96%] javac *.java; jar cvf -> gdcm.jar
----------
1. ERROR in gdcm/ImageToImageFilter.java (at line 44)
  public Image GetOutput() {
         ^^^^^
The return type is incompatible with PixmapToPixmapFilter.GetOutput()
...


'Image' is a subclass of 'Pixmap' and PixmapToPixmapFilter defines a
member function: Pixmap GetOutput().

Does anyone knows if covariant return type is allowed in Java ? Is
yes, why is this failing with some java implementation and not other ?

Thanks,
-- 
Mathieu