simplify methods

core/src/main/java/org/elasticsearch/search/aggregations/bucket/nested/NestedAggregator.java

@@ -118,7 +118,7 @@ class NestedAggregator extends BucketsAggregator implements SingleBucketAggregat
 
     private void processBufferedDocs() throws IOException {
         if (bufferingNestedLeafBucketCollector != null) {
-            bufferingNestedLeafBucketCollector.postCollect();
+            bufferingNestedLeafBucketCollector.processBufferedChildBuckets();
         }
     }
 
@@ -158,27 +158,27 @@ class NestedAggregator extends BucketsAggregator implements SingleBucketAggregat
             }
 
             if (currentParentDoc != parentDoc) {
-                processChildBuckets(currentParentDoc, bucketBuffer);
+                processBufferedChildBuckets();
                 currentParentDoc = parentDoc;
             }
             bucketBuffer.add(bucket);
         }
 
-        void processChildBuckets(int parentDoc, LongArrayList buckets) throws IOException {
+        void processBufferedChildBuckets() throws IOException {
             if (bucketBuffer.isEmpty()) {
                 return;
             }
 
 
-            final int prevParentDoc = parentDocs.prevSetBit(parentDoc - 1);
+            final int prevParentDoc = parentDocs.prevSetBit(currentParentDoc - 1);
             int childDocId = childDocs.docID();
             if (childDocId <= prevParentDoc) {
                 childDocId = childDocs.advance(prevParentDoc + 1);
             }
 
-            for (; childDocId < parentDoc; childDocId = childDocs.nextDoc()) {
-                final long[] buffer = buckets.buffer;
-                final int size = buckets.size();
+            for (; childDocId < currentParentDoc; childDocId = childDocs.nextDoc()) {
+                final long[] buffer = bucketBuffer.buffer;
+                final int size = bucketBuffer.size();
                 for (int i = 0; i < size; i++) {
                     collectBucket(sub, childDocId, buffer[i]);
                 }
@@ -186,10 +186,6 @@ class NestedAggregator extends BucketsAggregator implements SingleBucketAggregat
             bucketBuffer.clear();
         }
 
-        void postCollect() throws IOException {
-            processChildBuckets(currentParentDoc, bucketBuffer);
-        }
-
     }
 
 }