private Double parseToDouble(final String str) {
        if (Objects.isNull(str) || str.isEmpty()) {
            return null;
        }
        try {
            return Double.parseDouble(str);
        } catch (NumberFormatException e) {
            LOG.error("Failed to parse value. cause: {} ", e.getMessage());
            return null;
        }
    }
parse string to double.

@param str string
@return java.lang.Double
shenyu-admin/src/main/java/org/apache/shenyu/admin/scale/scaler/dynamic/ScaleRuleEvaluator.java