### Question:
CodesApi { public GetCodesResponse retrieveCode(Long codeId) throws ApiException { ApiResponse<GetCodesResponse> resp = retrieveCodeWithHttpInfo(codeId); return resp.getData(); } CodesApi();  CodesApi(ApiClient apiClient); ApiClient getApiClient(); void setApiClient(ApiClient apiClient); com.squareup.okhttp.Call createCodeCall(PostCodesRequest body, final ProgressResponseBody.ProgressListener progressListener, final ProgressRequestBody.ProgressRequestListener progressRequestListener); PostCodesResponse createCode(PostCodesRequest body); ApiResponse<PostCodesResponse> createCodeWithHttpInfo(PostCodesRequest body); com.squareup.okhttp.Call createCodeAsync(PostCodesRequest body, final ApiCallback<PostCodesResponse> callback); com.squareup.okhttp.Call deleteCodeCall(Long codeId, final ProgressResponseBody.ProgressListener progressListener, final ProgressRequestBody.ProgressRequestListener progressRequestListener); DeleteCodesResponse deleteCode(Long codeId); ApiResponse<DeleteCodesResponse> deleteCodeWithHttpInfo(Long codeId); com.squareup.okhttp.Call deleteCodeAsync(Long codeId, final ApiCallback<DeleteCodesResponse> callback); com.squareup.okhttp.Call retrieveCodeCall(Long codeId, final ProgressResponseBody.ProgressListener progressListener, final ProgressRequestBody.ProgressRequestListener progressRequestListener); GetCodesResponse retrieveCode(Long codeId); ApiResponse<GetCodesResponse> retrieveCodeWithHttpInfo(Long codeId); com.squareup.okhttp.Call retrieveCodeAsync(Long codeId, final ApiCallback<GetCodesResponse> callback); com.squareup.okhttp.Call retrieveCodesCall(final ProgressResponseBody.ProgressListener progressListener, final ProgressRequestBody.ProgressRequestListener progressRequestListener); List<GetCodesResponse> retrieveCodes(); ApiResponse<List<GetCodesResponse>> retrieveCodesWithHttpInfo(); com.squareup.okhttp.Call retrieveCodesAsync(final ApiCallback<List<GetCodesResponse>> callback); com.squareup.okhttp.Call updateCodeCall(Long codeId, PutCodesRequest body, final ProgressResponseBody.ProgressListener progressListener, final ProgressRequestBody.ProgressRequestListener progressRequestListener); PutCodesResponse updateCode(Long codeId, PutCodesRequest body); ApiResponse<PutCodesResponse> updateCodeWithHttpInfo(Long codeId, PutCodesRequest body); com.squareup.okhttp.Call updateCodeAsync(Long codeId, PutCodesRequest body, final ApiCallback<PutCodesResponse> callback);  }### Answer:
@Test public void retrieveCodeTest() throws ApiException { Long codeId = null; GetCodesResponse response = api.retrieveCode(codeId); }