Fix java.editor tests

[jlahoda]

This patch fixes various problems so that java.editor unit tests pass on JDK 8 and 11, and adds the tests into the GitHub Action configuration.

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[mbien]

excellent! Good to have the java.editor tests running again.

[singh-akhilesh]

LGTM

[mbien]

all green, two approvals -> merging, since the more editor tests we have active the better.