code: public Observable<P2SVpnServerConfigurationInner> getAsync(String resourceGroupName, String virtualWanName, String p2SVpnServerConfigurationName) {
          return getWithServiceResponseAsync(resourceGroupName, virtualWanName, p2SVpnServerConfigurationName).map(new Func1<ServiceResponse<P2SVpnServerConfigurationInner>, P2SVpnServerConfigurationInner>() {
              @Override
              public P2SVpnServerConfigurationInner call(ServiceResponse<P2SVpnServerConfigurationInner> response) {
                  return response.body();
              }
          });
      }
docs: Retrieves the details of a P2SVpnServerConfiguration.
  
  @param resourceGroupName The resource group name of the P2SVpnServerConfiguration.
  @param virtualWanName The name of the VirtualWan.
  @param p2SVpnServerConfigurationName The name of the P2SVpnServerConfiguration.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the P2SVpnServerConfigurationInner object