presto-main/src/main/java/io/prestosql/sql/planner/SubqueryPlanner.java/SubqueryPlanner/coercionsFor
class SubqueryPlanner:    private List<Expression> coercionsFor(Expression expression)
    {
        return analysis.getCoercions().keySet().stream()
                .map(NodeRef::getNode)
                .filter(coercionExpression -> coercionExpression.equals(expression))
                .collect(toImmutableList());
    }