presto-thrift-api/src/main/java/io/prestosql/plugin/thrift/api/PrestoThriftBlock.java/PrestoThriftBlock/theOnlyNonNull
class PrestoThriftBlock:    private static PrestoThriftColumnData theOnlyNonNull(PrestoThriftColumnData... columnsData)
    {
        PrestoThriftColumnData result = null;
        for (PrestoThriftColumnData data : columnsData) {
            if (data != null) {
                checkArgument(result == null, "more than one type is present");
                result = data;
            }
        }
        checkArgument(result != null, "no types are present");
        return result;
    }