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mvn -Pgenerate -Ddatabase=postgres clean -Dmaven.test.skip=true clean package
That command produces the datafiles in activiti-upgrade/src/test/resources/org/activiti/db/${project.version}/data. Bear in mind that the default directory name is based on the project version, which might contain the -SNAPSHOT. Then you can just manually change the directory name of the version.
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mvn -Pgenerate -Ddatabase=postgres -DupgradeVersion=5.8 clean -Dmaven.test.skip=true clean package
Run that generate profile for every database.
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