code: public Observable<ServiceResponse<CertificateBundle>> recoverDeletedCertificateWithServiceResponseAsync(String vaultBaseUrl, String certificateName) {
          if (vaultBaseUrl == null) {
              throw new IllegalArgumentException("Parameter vaultBaseUrl is required and cannot be null.");
          }
          if (certificateName == null) {
              throw new IllegalArgumentException("Parameter certificateName is required and cannot be null.");
          }
          if (this.apiVersion() == null) {
              throw new IllegalArgumentException("Parameter this.apiVersion() is required and cannot be null.");
          }
          String parameterizedHost = Joiner.on(", ").join("{vaultBaseUrl}", vaultBaseUrl);
          return service.recoverDeletedCertificate(certificateName, this.apiVersion(), this.acceptLanguage(), parameterizedHost, this.userAgent())
              .flatMap(new Func1<Response<ResponseBody>, Observable<ServiceResponse<CertificateBundle>>>() {
                  @Override
                  public Observable<ServiceResponse<CertificateBundle>> call(Response<ResponseBody> response) {
                      try {
                          ServiceResponse<CertificateBundle> clientResponse = recoverDeletedCertificateDelegate(response);
                          return Observable.just(clientResponse);
                      } catch (Throwable t) {
                          return Observable.error(t);
                      }
                  }
              });
      }
docs: Recovers the deleted certificate back to its current version under /certificates.
  The RecoverDeletedCertificate operation performs the reversal of the Delete operation. The operation is applicable in vaults enabled for soft-delete, and must be issued during the retention interval (available in the deleted certificate's attributes). This operation requires the certificates/recover permission.
  
  @param vaultBaseUrl The vault name, for example https://myvault.vault.azure.net.
  @param certificateName The name of the deleted certificate
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the CertificateBundle object