/usr/share/doc/libjgoodies-forms-java/api/com/jgoodies/forms/extras/ is in libjgoodies-forms-java-doc 1.6.0-4.
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/usr/share/doc/libjgoodies-forms-java/api/com/jgoodies/forms/extras/FormLayoutUtils.ConstraintIterator.html
/usr/share/doc/libjgoodies-forms-java/api/com/jgoodies/forms/extras/FormLayoutUtils.html
/usr/share/doc/libjgoodies-forms-java/api/com/jgoodies/forms/extras/class-use/
/usr/share/doc/libjgoodies-forms-java/api/com/jgoodies/forms/extras/class-use/FormLayoutUtils.ConstraintIterator.html
/usr/share/doc/libjgoodies-forms-java/api/com/jgoodies/forms/extras/class-use/FormLayoutUtils.html
/usr/share/doc/libjgoodies-forms-java/api/com/jgoodies/forms/extras/package-frame.html
/usr/share/doc/libjgoodies-forms-java/api/com/jgoodies/forms/extras/package-summary.html
/usr/share/doc/libjgoodies-forms-java/api/com/jgoodies/forms/extras/package-tree.html
/usr/share/doc/libjgoodies-forms-java/api/com/jgoodies/forms/extras/package-use.html