Upgrade to lucene-7.0.0-snapshot-ad2cb77. (#25349)

Most notable changes:
 - better update concurrency: LUCENE-7868
 - TopDocs.totalHits is now a long: LUCENE-7872
 - QueryBuilder does not remove the boolean query around multi-term synonyms:
   LUCENE-7878
 - removal of Fields: LUCENE-7500

For the `TopDocs.totalHits` change, this PR relies on the fact that the encoding
of vInts and vLongs are compatible: you can write and read with any of them as
long as the value can be represented by a positive int.

1 files changed, 6 insertions, 6 deletions

diff --git a/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionFieldStats.java b/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionFieldStats.java
index 8b5761a7e9..c9b8356362 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionFieldStats.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionFieldStats.java
@@ -20,7 +20,8 @@
 package org.elasticsearch.search.suggest.completion;
 
 import com.carrotsearch.hppc.ObjectLongHashMap;
-import org.apache.lucene.index.Fields;
+
+import org.apache.lucene.index.FieldInfo;
 import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.index.LeafReader;
 import org.apache.lucene.index.LeafReaderContext;
@@ -49,14 +50,13 @@ public class CompletionFieldStats {
         for (LeafReaderContext atomicReaderContext : indexReader.leaves()) {
             LeafReader atomicReader = atomicReaderContext.reader();
             try {
-                Fields fields = atomicReader.fields();
-                for (String fieldName : fields) {
-                    Terms terms = fields.terms(fieldName);
+                for (FieldInfo info : atomicReader.getFieldInfos()) {
+                    Terms terms = atomicReader.terms(info.name);
                     if (terms instanceof CompletionTerms) {
                         // TODO: currently we load up the suggester for reporting its size
                         long fstSize = ((CompletionTerms) terms).suggester().ramBytesUsed();
-                        if (fieldNamePatterns != null && fieldNamePatterns.length > 0 && Regex.simpleMatch(fieldNamePatterns, fieldName)) {
-                            completionFields.addTo(fieldName, fstSize);
+                        if (fieldNamePatterns != null && fieldNamePatterns.length > 0 && Regex.simpleMatch(fieldNamePatterns, info.name)) {
+                            completionFields.addTo(info.name, fstSize);
                         }
                         sizeInBytes += fstSize;
                     }