[Java] rework event module #128

All 133 tests pass in 5s

133 tests +2 133 ✔️ +2 5s ⏱️ ±0s
  16 suites ±0     0 💤 ±0
  16 files ±0     0 ❌ ±0

Results for commit 0857eb3. ± Comparison against earlier commit b26fb1c.