fix: Get boolean only if eventData has the key

[TatuLund]

Fixes: #12198

[github-actions]

Unit Test Results

   936 files  +  1     936 suites  +1   36m 23s ⏱️ -17s
6 098 tests +  6  6 048 ✔️ +  7  50 💤 ±0  0 ❌ ±0 
6 291 runs  +14  6 235 ✔️ +12  56 💤 +3  0 ❌ ±0 

Results for commit 20113e8. ± Comparison against base commit d650205.

♻️ This comment has been updated with latest results.

[mcollovati]

Does it make sense to add a test in ElementListenersTest for this change? Something like

AtomicInteger eventCount = new AtomicInteger();
DomListenerRegistration registration = ns.add("foo", e -> eventCount.incrementAndGet());
registration.setFilter("filterKey");

ns.fireEvent(createEvent("foo"));
Assert.assertEquals(0, eventCount.get());

JsonObject eventData = Json.createObject();
eventData.put("filterKey", true);
ns.fireEvent(new DomEvent(new Element("element"), "foo", eventData));
Assert.assertEquals(1, eventCount.get());

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
105 Code Smells

No Coverage information
0.2% Duplication

[vaadin-bot]

Hi @TatuLund and @mcollovati, when i performed cherry-pick to this commit to 2.7, i have encountered the following issue. Can you take a look and pick it manually?
Error Message:
Error: Command failed: git cherry-pick 992b236
error: could not apply 992b236... fix: Get boolean only if eventData has the key (#13021)
hint: after resolving the conflicts, mark the corrected paths
hint: with 'git add ' or 'git rm '
hint: and commit the result with 'git commit'