Generate one of the example plugins (Hello World) and look at 2 things:
MANIFEST.MF and build.properties. When I generate a plugin, my
build.properties looks like:
source.. = src/
output.. = bin/
bin.includes = plugin.xml,\
META-INF/,\
.,\
icons/,\
product_lg.gif,\
splash.bmp
"source..", "output..", and the ".,\" line in bin.includes are what puts
the .class files in the correct place in an exported plugin.
It looks odd because "." is the library name in source.<library> and
output.<library>.