code: public static BigDecimal getSystemConfigDecimal(String keyPrefix, IConfigKey key) {
          return systemConfigs.getDecimalConfig(keyPrefix, key);
      }
docs: Get system config decimal. Config key include prefix.
  Example:<br>
  If key.getKeyString() is "test", <br>
  getSystemConfigDecimal("1.", key); will return "1.test" config value in system config file.
  
  @param keyPrefix config key prefix
  @param key       config key
  @return config BigDecimal value. Return null if not config in
  system config file "{@value #DEFAULT_SYSTEM_CONFIG_ABSOLUTE_CLASS_PATH}" or self define system config path.
  @see #setSystemConfigs(String, OneProperties)