adding java docs

Author: benwtrent

server/src/main/java/org/elasticsearch/search/vectors/AbstractMaxScoreKnnCollector.java

@@ -13,14 +13,32 @@
 import org.apache.lucene.search.knn.KnnSearchStrategy;
 import org.elasticsearch.index.codec.vectors.cluster.NeighborQueue;
 
-public abstract class AbstractMaxScoreKnnCollector extends AbstractKnnCollector {
+/**
+ * Abstract class for collectors that maintain a maximum score for KNN search.
+ * It extends the {@link AbstractKnnCollector} and provides methods to manage
+ * the minimum competitive document score, useful for tracking competitive scores
+ * over multiple leaves.
+ */
+abstract class AbstractMaxScoreKnnCollector extends AbstractKnnCollector {
     public static final long LEAST_COMPETITIVE = NeighborQueue.encodeRaw(Integer.MAX_VALUE, Float.NEGATIVE_INFINITY);
 
     protected AbstractMaxScoreKnnCollector(int k, long visitLimit, KnnSearchStrategy searchStrategy) {
         super(k, visitLimit, searchStrategy);
     }
 
+    /**
+     * Returns the minimum competitive document score.
+     * This is used to determine the global competitiveness of documents in the search.
+     * This may be a competitive score even if the collector hasn't collected k results yet.
+     *
+     * @return the minimum competitive document score
+     */
     public abstract long getMinCompetitiveDocScore();
 
+    /**
+     * Updates the minimum competitive document score.
+     *
+     * @param minCompetitiveDocScore the new minimum competitive document score to set
+     */
     abstract void updateMinCompetitiveDocScore(long minCompetitiveDocScore);
 }

server/src/main/java/org/elasticsearch/search/vectors/IVFKnnSearchStrategy.java

@@ -48,6 +48,13 @@ public int hashCode() {
         return Objects.hashCode(visitRatio);
     }
 
+    /**
+     * This method is called when the next block of vectors is processed.
+     * It accumulates the minimum competitive document score from the collector
+     * and updates the accumulator with the most competitive score.
+     * If the current score in the accumulator is greater than the minimum competitive
+     * document score in the collector, it updates the collector's minimum competitive document score.
+     */
     @Override
     public void nextVectorsBlock() {
         if (accumulator == null) {