code: public Observable<ClusterInner> getAsync(String resourceGroupName, String workspaceName, String clusterName) {
          return getWithServiceResponseAsync(resourceGroupName, workspaceName, clusterName).map(new Func1<ServiceResponse<ClusterInner>, ClusterInner>() {
              @Override
              public ClusterInner call(ServiceResponse<ClusterInner> response) {
                  return response.body();
              }
          });
      }
docs: Gets information about a Cluster.
  
  @param resourceGroupName Name of the resource group to which the resource belongs.
  @param workspaceName The name of the workspace. Workspace names can only contain a combination of alphanumeric characters along with dash (-) and underscore (_). The name must be from 1 through 64 characters long.
  @param clusterName The name of the cluster within the specified resource group. Cluster names can only contain a combination of alphanumeric characters along with dash (-) and underscore (_). The name must be from 1 through 64 characters long.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the ClusterInner object