[JUnit Platform Engine] Don't use Java 9+ APIs (#3025)

Even though Java 8 is ancient, Cucumber should still work on it.

Author: mpkorstanje

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Fixed
+- [JUnit Platform Engine] Don't use Java 9+ APIs ([#3025](https://github.com/cucumber/cucumber-jvm/pull/3025) M.P. Korstanje)
 - [JUnit Platform Engine] Implement toString on custom DiscoverySelectors
 
 ## [7.25.0] - 2025-07-10

cucumber-junit-platform-engine/src/main/java/io/cucumber/junit/platform/engine/FeatureResolver.java

@@ -130,14 +130,13 @@ public Resolution resolve(FeatureWithLinesSelector selector) {
 
     @Override
     public Resolution resolve(FileSelector selector, Context context) {
-        Set<DiscoverySelector> selectors = featureParser.parseResource(selector.getPath())
-                .stream()
-                .map(feature -> selector.getPosition()
+        Set<FeatureElementSelector> selectors = featureParser.parseResource(selector.getPath())
+                .flatMap(feature -> selector.getPosition()
                         .map(position -> selectElementAt(feature, position))
                         .orElseGet(() -> Optional.of(selectFeature(feature))))
-                .filter(Optional::isPresent)
-                .map(Optional::get)
-                .collect(toSet());
+                .map(Collections::singleton)
+                .orElseGet(Collections::emptySet);
+
         return toResolution(selectors);
     }