code: protected BigDecimal getDecimalConfig(IConfigKey key) {
          String value = getConfig(key);
          if (value == null) {
              return null;
          }
          return new BigDecimal(value);
      }
docs: <p>Get config decimal value. For all number config.</p>
  If not config will return null.
  
  @param key config key
  @return BigDecimal object.
  @see BigDecimal