code: public Observable<ServiceResponse<VaultAccessPolicyParametersInner>> updateAccessPolicyWithServiceResponseAsync(String resourceGroupName, String vaultName, AccessPolicyUpdateKind operationKind, VaultAccessPolicyProperties properties) {
          if (resourceGroupName == null) {
              throw new IllegalArgumentException("Parameter resourceGroupName is required and cannot be null.");
          }
          if (vaultName == null) {
              throw new IllegalArgumentException("Parameter vaultName is required and cannot be null.");
          }
          if (operationKind == null) {
              throw new IllegalArgumentException("Parameter operationKind is required and cannot be null.");
          }
          if (this.client.subscriptionId() == null) {
              throw new IllegalArgumentException("Parameter this.client.subscriptionId() is required and cannot be null.");
          }
          if (this.client.apiVersion() == null) {
              throw new IllegalArgumentException("Parameter this.client.apiVersion() is required and cannot be null.");
          }
          if (properties == null) {
              throw new IllegalArgumentException("Parameter properties is required and cannot be null.");
          }
          Validator.validate(properties);
          VaultAccessPolicyParametersInner parameters = new VaultAccessPolicyParametersInner();
          parameters.withProperties(properties);
          return service.updateAccessPolicy(resourceGroupName, vaultName, operationKind, this.client.subscriptionId(), this.client.apiVersion(), this.client.acceptLanguage(), parameters, this.client.userAgent())
              .flatMap(new Func1<Response<ResponseBody>, Observable<ServiceResponse<VaultAccessPolicyParametersInner>>>() {
                  @Override
                  public Observable<ServiceResponse<VaultAccessPolicyParametersInner>> call(Response<ResponseBody> response) {
                      try {
                          ServiceResponse<VaultAccessPolicyParametersInner> clientResponse = updateAccessPolicyDelegate(response);
                          return Observable.just(clientResponse);
                      } catch (Throwable t) {
                          return Observable.error(t);
                      }
                  }
              });
      }
docs: Update access policies in a key vault in the specified subscription.
  
  @param resourceGroupName The name of the Resource Group to which the vault belongs.
  @param vaultName Name of the vault
  @param operationKind Name of the operation. Possible values include: 'add', 'replace', 'remove'
  @param properties Properties of the access policy
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the VaultAccessPolicyParametersInner object