presto-main/src/main/java/io/prestosql/sql/gen/ExpressionCompiler.java/CacheKey/toString
class CacheKey:        @Override
        public String toString()
        {
            return toStringHelper(this)
                    .add("filter", filter)
                    .add("projections", projections)
                    .add("uniqueKey", uniqueKey)
                    .toString();
        }