src/main/java/com/conveyal/gtfs/loader/JdbcGtfsLoader.java
private void setFieldToNull(boolean postgresText, String[] transformedStrings, int fieldIndex, Field field) {
        if (postgresText) transformedStrings[fieldIndex + 1] = POSTGRES_NULL_TEXT;
        // Adjust parameter index by two: indexes are one-based and the first one is the CSV line number.
        else try {
            // LOG.info("setting {} index to null", fieldIndex + 2);
            field.setNull(insertStatement, fieldIndex + 2);
        } catch (SQLException e) {
            e.printStackTrace();
            // FIXME: store error here? It appears that an exception should only be thrown if the type value is invalid,
            // the connection is closed, or the index is out of bounds. So storing an error may be unnecessary.
        }
    }
private void setFieldToNull(boolean postgresText, String[] transformedStrings, int fieldIndex, Field field) {
        if (postgresText) transformedStrings[fieldIndex + 1] = POSTGRES_NULL_TEXT;
        // Adjust parameter index by two: indexes are one-based and the first one is the CSV line number.
        else try {
            // LOG.info("setting {} index to null", fieldIndex + 2);
            field.setNull(insertStatement, fieldIndex + 2);
        } catch (SQLException e) {
            e.printStackTrace();
            // FIXME: store error here? It appears that an exception should only be thrown if the type value is invalid,
            // the connection is closed, or the index is out of bounds. So storing an error may be unnecessary.
        }
    }
Sets field to null in statement or string array depending on whether postgres is being used.