code: public static BigDecimal getHavePathSelfConfigDecimal(String keyPrefix, IConfigKeyWithPath key) {
          String configAbsoluteClassPath = key.getConfigPath();
          return getSelfConfigDecimal(configAbsoluteClassPath, keyPrefix, key);
      }
docs: Get self config decimal. Config key include prefix.
  Example:<br>
  If key.getKeyString() is "test", <br>
  getSelfConfigDecimal("1.", key);
  will return "1.test" config value in {@linkplain IConfigKeyWithPath#getConfigPath() path} set in key.
  
  @param keyPrefix config key prefix
  @param key       config key with configAbsoluteClassPath in config file
  @return config BigDecimal value. Return null if not add config file or not config in config file.
  @see #addSelfConfigs(String, OneProperties)