presto-spi/src/main/java/io/prestosql/spi/predicate/SortedRangeSet.java/SortedRangeSet/getSingleValue
class SortedRangeSet:    @Override
    public Object getSingleValue()
    {
        if (!isSingleValue()) {
            throw new IllegalStateException("SortedRangeSet does not have just a single value");
        }
        return lowIndexedRanges.values().iterator().next().getSingleValue();
    }