presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/ImplementExceptAsUnion.java/ImplementExceptAsUnion/ImplementExceptAsUnion
class ImplementExceptAsUnion:    public ImplementExceptAsUnion(Metadata metadata)
    {
        this.metadata = requireNonNull(metadata, "metadata is null");
    }