docs: public Observable<List<DatabasePrincipalInner>> listPrincipalsAsync(String resourceGroupName, String clusterName, String databaseName) {
          return listPrincipalsWithServiceResponseAsync(resourceGroupName, clusterName, databaseName).map(new Func1<ServiceResponse<List<DatabasePrincipalInner>>, List<DatabasePrincipalInner>>() {
              @Override
              public List<DatabasePrincipalInner> call(ServiceResponse<List<DatabasePrincipalInner>> response) {
                  return response.body();
              }
          });
      }