docs: public static boolean addProvider() {
          boolean result = false;
  
          if (provider == null) {
  
              // Check whether the provider has already been installed:
              Provider provider = Security.getProvider(providerName);
  
              // If not, attempt to install it:
              if (provider == null) {
                  if ((provider = instantiate()) != null) {
                      Security.addProvider(provider);
                  }
              }
  
              // Now cache the provider:
              SecurityProvider.provider = provider;
  
              result = provider != null;
          }
  
          return result;
      }