presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/ExtractSpatialJoins.java/ExtractSpatialJoins/toExpression
class ExtractSpatialJoins:    private static Expression toExpression(Optional<Symbol> optionalSymbol, Expression defaultExpression)
    {
        return optionalSymbol.map(symbol -> (Expression) symbol.toSymbolReference()).orElse(defaultExpression);
    }