Bug 21249

I'm developing several Ant listeners to do various checks on the outputs of our
build process.  One of these tests is to run the DocCheck (javadoc validation)
doclet on each <javadoc> task that gets run as a part of our build.  This allows
us to make sure that the javadoc documentation is accurate.  Unfortunately,
there are no getter methods on the javadoc task, so I can't determine what
values werre set in the javadoc task.  As a result, the only way I can run the
DocCheck doclet is to set the doclet, the doclet path, and the output directory
on the existing javadoc task, the execute() the task again.  This works in some
cases, but the DocCheck doclet fails when there are "-list ..." options passed
to the javadoc command.  And there's no way to clear these from the javadoc
task, so the only thing I can do is catch the BuildException and log it -- I
can't even tell what source files were passed into the javadoc command because
all of the interesting properties of the Javadoc object are very private...