Fix GeoGridTestCase#toXContent (#85093)

This change make sure we create a valid random instance for GeoGridTestCase.

Author: iverase

server/src/test/java/org/elasticsearch/search/aggregations/bucket/geogrid/GeoGridTestCase.java

@@ -56,14 +56,19 @@ protected T createTestInstance(String name, Map<String, Object> metadata, Intern
         final int precision = randomPrecision();
         int size = randomNumberOfBuckets();
         List<InternalGeoGridBucket> buckets = new ArrayList<>(size);
+        final List<Long> seen = new ArrayList<>(size);
+        int finalSize = 0;
         for (int i = 0; i < size; i++) {
             double latitude = randomDoubleBetween(-90.0, 90.0, false);
             double longitude = randomDoubleBetween(-180.0, 180.0, false);
-
             long hashAsLong = longEncode(longitude, latitude, precision);
-            buckets.add(createInternalGeoGridBucket(hashAsLong, randomInt(IndexWriter.MAX_DOCS), aggregations));
+            if (seen.contains(hashAsLong) == false) { // make sure we don't add twice the same bucket
+                buckets.add(createInternalGeoGridBucket(hashAsLong, randomInt(IndexWriter.MAX_DOCS), aggregations));
+                seen.add(hashAsLong);
+                finalSize++;
+            }
         }
-        return createInternalGeoGrid(name, size, buckets, metadata);
+        return createInternalGeoGrid(name, finalSize, buckets, metadata);
     }
 
     @Override