presto-main/src/main/java/io/prestosql/operator/OperatorStats.java/OperatorStats/getMergeableInfoOrNull
class OperatorStats:    @SuppressWarnings("unchecked")
    private static Mergeable<OperatorInfo> getMergeableInfoOrNull(OperatorInfo info)
    {
        Mergeable<OperatorInfo> base = null;
        if (info instanceof Mergeable) {
            base = (Mergeable<OperatorInfo>) info;
        }
        return base;
    }