presto-main/src/main/java/io/prestosql/sql/planner/Partitioning.java/Partitioning/ArgumentBinding
class Partitioning:        @JsonCreator
        public ArgumentBinding(
                @JsonProperty("expression") Expression expression,
                @JsonProperty("constant") NullableValue constant)
        {
            this.expression = expression;
            this.constant = constant;
            checkArgument((expression == null) != (constant == null), "Either expression or constant must be set");
        }