LUCENE-9599: fix compilation issue in Java 8
diff --git a/lucene/core/src/java/org/apache/lucene/search/TopFieldCollector.java b/lucene/core/src/java/org/apache/lucene/search/TopFieldCollector.java
index 219f435..52b3da2 100644
--- a/lucene/core/src/java/org/apache/lucene/search/TopFieldCollector.java
+++ b/lucene/core/src/java/org/apache/lucene/search/TopFieldCollector.java
@@ -419,7 +419,7 @@
           && queueFull
           && hitsThresholdChecker.isThresholdReached()) {
       assert bottom != null;
-      float minScore = (float) firstComparator.value(bottom.slot);
+      float minScore = (Float) firstComparator.value(bottom.slot);
       if (minScore > minCompetitiveScore) {
         scorer.setMinCompetitiveScore(minScore);
         minCompetitiveScore = minScore;