code: public Observable<Page<SecurityRuleInner>> listAsync(final String resourceGroupName, final String networkSecurityGroupName) {
          return listWithServiceResponseAsync(resourceGroupName, networkSecurityGroupName)
              .map(new Func1<ServiceResponse<Page<SecurityRuleInner>>, Page<SecurityRuleInner>>() {
                  @Override
                  public Page<SecurityRuleInner> call(ServiceResponse<Page<SecurityRuleInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Gets all security rules in a network security group.
  
  @param resourceGroupName The name of the resource group.
  @param networkSecurityGroupName The name of the network security group.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;SecurityRuleInner&gt; object