public void setSearcherSpecificMetaData(Searcher searcher, Object data) {
        if (searcherSpecificMetaData == null) {
            if (data != null)
                searcherSpecificMetaData = Map.of(searcher, data);
        } else {
            if (searcherSpecificMetaData.size() == 1) {
                if (searcherSpecificMetaData.containsKey(searcher)) {
                    searcherSpecificMetaData = (data != null) ? Map.of(searcher, data) : null;
                } else {
                    searcherSpecificMetaData = new TreeMap<>(searcherSpecificMetaData);
                    searcherSpecificMetaData.put(searcher, data);
                }
            } else {
                searcherSpecificMetaData.put(searcher, data);
            }
        }
    }
Attach some data to this hit for this searcher
container-search/src/main/java/com/yahoo/search/result/Hit.java