docs: protected final void readExisting(
              SslConfiguration defaultSslConfiguration,
              KeyConfiguration defaultKeyConfiguration,
              KeyStoreConfiguration defaultKeyStoreConfiguration,
              TrustStoreConfiguration defaultTrustStoreConfiguration) {
          if (defaultKeyConfiguration != null) {
              this.key = defaultKeyConfiguration;
          }
          if (defaultKeyStoreConfiguration != null) {
              this.keyStore = defaultKeyStoreConfiguration;
          }
          if (defaultKeyConfiguration != null) {
              this.trustStore = defaultTrustStoreConfiguration;
          }
          if (defaultSslConfiguration != null) {
              this.port = defaultSslConfiguration.getPort();
              this.enabled = defaultSslConfiguration.isEnabled();
              this.buildSelfSigned = defaultSslConfiguration.buildSelfSigned();
              defaultSslConfiguration.getProtocols().ifPresent(strings -> this.protocols = strings);
              defaultSslConfiguration.getProtocol().ifPresent(protocol -> this.protocol = protocol);
              defaultSslConfiguration.getCiphers().ifPresent(ciphers -> this.ciphers = ciphers);
              defaultSslConfiguration.getClientAuthentication().ifPresent(ca -> this.clientAuthentication = ca);
          }
      }