@Override
  public String defaultValue(final ArgSpec argSpec) throws Exception {
    for (final IDefaultValueProvider provider : defaultValueProviders) {
      final String defaultValue = provider.defaultValue(argSpec);
      if (defaultValue != null) {
        return defaultValue;
      }
    }
    return null;
  }
Instantiates a new Cascading default provider.

@param defaultValueProviders List of default value providers
app/src/main/java/org/hyperledger/besu/cli/util/CascadingDefaultProvider.java