Ant is a necessary requisite for OpenOffice.org compilation process starting with 680 base tree (2.0 branch). OpenOffice.org use the "java" method of calling it, ie. directly. This method is deprecated as of Ant 1.6 (see RELEASE NOTES for version 1.6.0):
...
ant.jar's manifest does no longer include a Class-Path entry, so it is no longer
possible to run Ant via java -jar ant.jar without manually altering the
CLASSPATH.
This issue is solved in #i23464#.
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