@Override
        public void accept(SqlStatement stmt, String key) {
            stmt.define(key, "null");
        }
<p>Render the keyword {@code null} in the query, useful e.g. in postgresql where "in ()" is invalid syntax.</p>
<p>
{@code select * from things where x in (null)}
core/src/main/java/org/jdbi/v3/core/statement/EmptyHandling.java