### Question:
ClientTransactionApi { public GetClientsClientIdTransactionsTransactionIdResponse retrieveClientTransaction(Long clientId, Long transactionId) throws ApiException { ApiResponse<GetClientsClientIdTransactionsTransactionIdResponse> resp = retrieveClientTransactionWithHttpInfo(clientId, transactionId); return resp.getData(); } ClientTransactionApi();  ClientTransactionApi(ApiClient apiClient); ApiClient getApiClient(); void setApiClient(ApiClient apiClient); com.squareup.okhttp.Call retrieveAllClientTransactionsCall(Long clientId, Integer offset, Integer limit, final ProgressResponseBody.ProgressListener progressListener, final ProgressRequestBody.ProgressRequestListener progressRequestListener); GetClientsClientIdTransactionsResponse retrieveAllClientTransactions(Long clientId, Integer offset, Integer limit); ApiResponse<GetClientsClientIdTransactionsResponse> retrieveAllClientTransactionsWithHttpInfo(Long clientId, Integer offset, Integer limit); com.squareup.okhttp.Call retrieveAllClientTransactionsAsync(Long clientId, Integer offset, Integer limit, final ApiCallback<GetClientsClientIdTransactionsResponse> callback); com.squareup.okhttp.Call retrieveClientTransactionCall(Long clientId, Long transactionId, final ProgressResponseBody.ProgressListener progressListener, final ProgressRequestBody.ProgressRequestListener progressRequestListener); GetClientsClientIdTransactionsTransactionIdResponse retrieveClientTransaction(Long clientId, Long transactionId); ApiResponse<GetClientsClientIdTransactionsTransactionIdResponse> retrieveClientTransactionWithHttpInfo(Long clientId, Long transactionId); com.squareup.okhttp.Call retrieveClientTransactionAsync(Long clientId, Long transactionId, final ApiCallback<GetClientsClientIdTransactionsTransactionIdResponse> callback); com.squareup.okhttp.Call undoClientTransactionCall(Long clientId, Long transactionId, String command, final ProgressResponseBody.ProgressListener progressListener, final ProgressRequestBody.ProgressRequestListener progressRequestListener); PostClientsClientIdTransactionsTransactionIdResponse undoClientTransaction(Long clientId, Long transactionId, String command); ApiResponse<PostClientsClientIdTransactionsTransactionIdResponse> undoClientTransactionWithHttpInfo(Long clientId, Long transactionId, String command); com.squareup.okhttp.Call undoClientTransactionAsync(Long clientId, Long transactionId, String command, final ApiCallback<PostClientsClientIdTransactionsTransactionIdResponse> callback);  }### Answer:
@Test public void retrieveClientTransactionTest() throws ApiException { Long clientId = null; Long transactionId = null; ClientTransactionData response = api.retrieveClientTransaction(clientId, transactionId); }