private void initHttpEngine() throws IOException {
  if (httpEngineFailure != null) {
    throw httpEngineFailure;
  } else if (httpEngine != null) {
    return;
  }

  connected = true;
  try {
    if (doOutput) {
      if (method.equals("GET")) {
        // they are requesting a stream to write to. This implies a POST method
        method = "POST";
      } else if (!HttpMethod.permitsRequestBody(method)) {
        throw new ProtocolException(method + " does not support writing");
      }
    }
    // If the user set content length to zero, we know there will not be a request body.
    httpEngine = newHttpEngine(method, null, null, null);
  } catch (IOException e) {
    httpEngineFailure = e;
    throw e;
  }
}
 

/**
 * Build an HTTP request with the given options.
 *
 * @param path The sub-path of the HTTP URL
 * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
 * @param queryParams The query parameters
 * @param collectionQueryParams The collection query parameters
 * @param body The request body object
 * @param headerParams The header parameters
 * @param formParams The form parameters
 * @param authNames The authentications to apply
 * @param progressRequestListener Progress request listener
 * @return The HTTP request
 * @throws ApiException If fail to serialize the request body object
 */
public Request buildRequest(String path, String method, List<Pair> queryParams, List<Pair> collectionQueryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {

    final String url = buildUrl(path, queryParams, collectionQueryParams);
    final Request.Builder reqBuilder = new Request.Builder().url(url);
    processHeaderParams(headerParams, reqBuilder);

    String contentType = (String) headerParams.get("Content-Type");
    // ensuring a default content type
    if (contentType == null) {
        contentType = "application/json";
    }

    RequestBody reqBody;
    if (!HttpMethod.permitsRequestBody(method)) {
        reqBody = null;
    } else if ("application/x-www-form-urlencoded".equals(contentType)) {
        reqBody = buildRequestBodyFormEncoding(formParams);
    } else if ("multipart/form-data".equals(contentType)) {
        reqBody = buildRequestBodyMultipart(formParams);
    } else if (body == null) {
        if ("DELETE".equals(method)) {
            // allow calling DELETE without sending a request body
            reqBody = null;
        } else {
            // use an empty request body (for POST, PUT and PATCH)
            reqBody = RequestBody.create(MediaType.parse(contentType), "");
        }
    } else {
        reqBody = serialize(body, contentType);
    }

    Request request = null;

    if(progressRequestListener != null && reqBody != null) {
        ProgressRequestBody progressRequestBody = new ProgressRequestBody(reqBody, progressRequestListener);
        request = reqBuilder.method(method, progressRequestBody).build();
    } else {
        request = reqBuilder.method(method, reqBody).build();
    }

    request = updateParamsForAuth(request);

    return request;
}
 

/**
 * Build an HTTP request with the given options.
 *
 * @param path The sub-path of the HTTP URL
 * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
 * @param queryParams The query parameters
 * @param collectionQueryParams The collection query parameters
 * @param body The request body object
 * @param headerParams The header parameters
 * @param formParams The form parameters
 * @param authNames The authentications to apply
 * @param progressRequestListener Progress request listener
 * @return The HTTP request
 * @throws ApiException If fail to serialize the request body object
 */
public Request buildRequest(String path, String method, List<Pair> queryParams, List<Pair> collectionQueryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {

    final String url = buildUrl(path, queryParams, collectionQueryParams);
    final Request.Builder reqBuilder = new Request.Builder().url(url);
    processHeaderParams(headerParams, reqBuilder);

    String contentType = (String) headerParams.get("Content-Type");
    // ensuring a default content type
    if (contentType == null) {
        contentType = "application/json";
    }

    RequestBody reqBody;
    if (!HttpMethod.permitsRequestBody(method)) {
        reqBody = null;
    } else if ("application/x-www-form-urlencoded".equals(contentType)) {
        reqBody = buildRequestBodyFormEncoding(formParams);
    } else if ("multipart/form-data".equals(contentType)) {
        reqBody = buildRequestBodyMultipart(formParams);
    } else if (body == null) {
        if ("DELETE".equals(method)) {
            // allow calling DELETE without sending a request body
            reqBody = null;
        } else {
            // use an empty request body (for POST, PUT and PATCH)
            reqBody = RequestBody.create(MediaType.parse(contentType), "");
        }
    } else {
        reqBody = serialize(body, contentType);
    }

    Request request = null;

    if(progressRequestListener != null && reqBody != null) {
        ProgressRequestBody progressRequestBody = new ProgressRequestBody(reqBody, progressRequestListener);
        request = reqBuilder.method(method, progressRequestBody).build();
    } else {
        request = reqBuilder.method(method, reqBody).build();
    }

    request = updateParamsForAuth(request);

    return request;
}
 

/**
 * Build an HTTP request with the given options.
 *
 * @param path The sub-path of the HTTP URL
 * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
 * @param queryParams The query parameters
 * @param collectionQueryParams The collection query parameters
 * @param body The request body object
 * @param headerParams The header parameters
 * @param formParams The form parameters
 * @param authNames The authentications to apply
 * @param progressRequestListener Progress request listener
 * @return The HTTP request 
 * @throws ApiException If fail to serialize the request body object
 */
public Request buildRequest(String path, String method, List<Pair> queryParams, List<Pair> collectionQueryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {
    updateParamsForAuth(authNames, queryParams, headerParams);

    final String url = buildUrl(path, queryParams, collectionQueryParams);
    final Request.Builder reqBuilder = new Request.Builder().url(url);
    processHeaderParams(headerParams, reqBuilder);

    String contentType = (String) headerParams.get("Content-Type");
    // ensuring a default content type
    if (contentType == null) {
        contentType = "application/json";
    }

    RequestBody reqBody;
    if (!HttpMethod.permitsRequestBody(method)) {
        reqBody = null;
    } else if ("application/x-www-form-urlencoded".equals(contentType)) {
        reqBody = buildRequestBodyFormEncoding(formParams);
    } else if ("multipart/form-data".equals(contentType)) {
        reqBody = buildRequestBodyMultipart(formParams);
    } else if (body == null) {
        if ("DELETE".equals(method)) {
            // allow calling DELETE without sending a request body
            reqBody = null;
        } else {
            // use an empty request body (for POST, PUT and PATCH)
            reqBody = RequestBody.create(MediaType.parse(contentType), "");
        }
    } else {
        reqBody = serialize(body, contentType);
    }

    Request request = null;

    if(progressRequestListener != null && reqBody != null) {
        ProgressRequestBody progressRequestBody = new ProgressRequestBody(reqBody, progressRequestListener);
        request = reqBuilder.method(method, progressRequestBody).build();
    } else {
        request = reqBuilder.method(method, reqBody).build();
    }

    return request;
}
 

/**
 * Build an HTTP request with the given options.
 *
 * @param path The sub-path of the HTTP URL
 * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
 * @param queryParams The query parameters
 * @param collectionQueryParams The collection query parameters
 * @param body The request body object
 * @param headerParams The header parameters
 * @param formParams The form parameters
 * @param authNames The authentications to apply
 * @param progressRequestListener Progress request listener
 * @return The HTTP request 
 * @throws ApiException If fail to serialize the request body object
 */
public Request buildRequest(String path, String method, List<Pair> queryParams, List<Pair> collectionQueryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {
    updateParamsForAuth(authNames, queryParams, headerParams);

    final String url = buildUrl(path, queryParams, collectionQueryParams);
    final Request.Builder reqBuilder = new Request.Builder().url(url);
    processHeaderParams(headerParams, reqBuilder);

    String contentType = (String) headerParams.get("Content-Type");
    // ensuring a default content type
    if (contentType == null) {
        contentType = "application/json";
    }

    RequestBody reqBody;
    if (!HttpMethod.permitsRequestBody(method)) {
        reqBody = null;
    } else if ("application/x-www-form-urlencoded".equals(contentType)) {
        reqBody = buildRequestBodyFormEncoding(formParams);
    } else if ("multipart/form-data".equals(contentType)) {
        reqBody = buildRequestBodyMultipart(formParams);
    } else if (body == null) {
        if ("DELETE".equals(method)) {
            // allow calling DELETE without sending a request body
            reqBody = null;
        } else {
            // use an empty request body (for POST, PUT and PATCH)
            reqBody = RequestBody.create(MediaType.parse(contentType), "");
        }
    } else {
        reqBody = serialize(body, contentType);
    }

    Request request = null;

    if(progressRequestListener != null && reqBody != null) {
        ProgressRequestBody progressRequestBody = new ProgressRequestBody(reqBody, progressRequestListener);
        request = reqBuilder.method(method, progressRequestBody).build();
    } else {
        request = reqBuilder.method(method, reqBody).build();
    }

    return request;
}
 

/**
 * Build HTTP call with the given options.
 *
 * @param path The sub-path of the HTTP URL
 * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
 * @param queryParams The query parameters
 * @param body The request body object
 * @param headerParams The header parameters
 * @param formParams The form parameters
 * @param authNames The authentications to apply
 * @param progressRequestListener Progress request listener
 * @return The HTTP call
 * @throws ApiException If fail to serialize the request body object
 */
public Call buildCall(String path, String method, List<Pair> queryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {
    updateParamsForAuth(authNames, queryParams, headerParams);

    final String url = buildUrl(path, queryParams);
    final Request.Builder reqBuilder = new Request.Builder().url(url);
    processHeaderParams(headerParams, reqBuilder);

    String contentType = (String) headerParams.get("Content-Type");
    // ensuring a default content type
    if (contentType == null) {
        contentType = "application/json";
    }

    RequestBody reqBody;
    if (!HttpMethod.permitsRequestBody(method)) {
        reqBody = null;
    } else if ("application/x-www-form-urlencoded".equals(contentType)) {
        reqBody = buildRequestBodyFormEncoding(formParams);
    } else if ("multipart/form-data".equals(contentType)) {
        reqBody = buildRequestBodyMultipart(formParams);
    } else if (body == null) {
        if ("DELETE".equals(method)) {
            // allow calling DELETE without sending a request body
            reqBody = null;
        } else {
            // use an empty request body (for POST, PUT and PATCH)
            reqBody = RequestBody.create(MediaType.parse(contentType), "");
        }
    } else {
        reqBody = serialize(body, contentType);
    }

    Request request = null;

    if(progressRequestListener != null && reqBody != null) {
        ProgressRequestBody progressRequestBody = new ProgressRequestBody(reqBody, progressRequestListener);
        request = reqBuilder.method(method, progressRequestBody).build();
    } else {
        request = reqBuilder.method(method, reqBody).build();
    }

    return httpClient.newCall(request);
}
 

/**
 * Build an HTTP request with the given options.
 *
 * @param path The sub-path of the HTTP URL
 * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
 * @param queryParams The query parameters
 * @param collectionQueryParams The collection query parameters
 * @param body The request body object
 * @param headerParams The header parameters
 * @param formParams The form parameters
 * @param authNames The authentications to apply
 * @param progressRequestListener Progress request listener
 * @return The HTTP request 
 * @throws ApiException If fail to serialize the request body object
 */
public Request buildRequest(String path, String method, List<Pair> queryParams, List<Pair> collectionQueryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {
    updateParamsForAuth(authNames, queryParams, headerParams);

    final String url = buildUrl(path, queryParams, collectionQueryParams);
    final Request.Builder reqBuilder = new Request.Builder().url(url);
    processHeaderParams(headerParams, reqBuilder);

    String contentType = (String) headerParams.get("Content-Type");
    // ensuring a default content type
    if (contentType == null) {
        contentType = "application/json";
    }

    RequestBody reqBody;
    if (!HttpMethod.permitsRequestBody(method)) {
        reqBody = null;
    } else if ("application/x-www-form-urlencoded".equals(contentType)) {
        reqBody = buildRequestBodyFormEncoding(formParams);
    } else if ("multipart/form-data".equals(contentType)) {
        reqBody = buildRequestBodyMultipart(formParams);
    } else if (body == null) {
        if ("DELETE".equals(method)) {
            // allow calling DELETE without sending a request body
            reqBody = null;
        } else {
            // use an empty request body (for POST, PUT and PATCH)
            reqBody = RequestBody.create(MediaType.parse(contentType), "");
        }
    } else {
        reqBody = serialize(body, contentType);
    }

    Request request = null;

    if(progressRequestListener != null && reqBody != null) {
        ProgressRequestBody progressRequestBody = new ProgressRequestBody(reqBody, progressRequestListener);
        request = reqBuilder.method(method, progressRequestBody).build();
    } else {
        request = reqBuilder.method(method, reqBody).build();
    }

    return request;
}
 

/**
 * Build HTTP call with the given options.
 *
 * @param path The sub-path of the HTTP URL
 * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
 * @param queryParams The query parameters
 * @param body The request body object
 * @param headerParams The header parameters
 * @param formParams The form parameters
 * @param authNames The authentications to apply
 * @param progressRequestListener Progress request listener
 * @return The HTTP call
 * @throws ApiException If fail to serialize the request body object
 */
public Call buildCall(String path, String method, List<Pair> queryParams, Object body,
        Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames,
        ProgressRequestBody.ProgressRequestListener progressRequestListener)
        throws ApiException {
    updateParamsForAuth(authNames, queryParams, headerParams);

    final String url = buildUrl(path, queryParams);
    final Request.Builder reqBuilder = new Request.Builder().url(url);
    processHeaderParams(headerParams, reqBuilder);

    String contentType = (String) headerParams.get("Content-Type");
    // ensuring a default content type
    if (contentType == null) {
        contentType = "application/json";
    }

    RequestBody reqBody;
    if (!HttpMethod.permitsRequestBody(method)) {
        reqBody = null;
    } else if ("application/x-www-form-urlencoded".equals(contentType)) {
        reqBody = buildRequestBodyFormEncoding(formParams);
    } else if ("multipart/form-data".equals(contentType)) {
        reqBody = buildRequestBodyMultipart(formParams);
    } else if (body == null) {
        if ("DELETE".equals(method)) {
            // allow calling DELETE without sending a request body
            reqBody = null;
        } else {
            // use an empty request body (for POST, PUT and PATCH)
            reqBody = RequestBody.create(MediaType.parse(contentType), "");
        }
    } else {
        reqBody = serialize(body, contentType);
    }

    Request request = null;

    if (progressRequestListener != null && reqBody != null) {
        ProgressRequestBody progressRequestBody = new ProgressRequestBody(reqBody,
                progressRequestListener);
        request = reqBuilder.method(method, progressRequestBody).build();
    } else {
        request = reqBuilder.method(method, reqBody).build();
    }

    return httpClient.newCall(request);
}
 

/**
 * Build an HTTP request with the given options.
 *
 * @param path The sub-path of the HTTP URL
 * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
 * @param queryParams The query parameters
 * @param collectionQueryParams The collection query parameters
 * @param body The request body object
 * @param headerParams The header parameters
 * @param formParams The form parameters
 * @param authNames The authentications to apply
 * @param progressRequestListener Progress request listener
 * @return The HTTP request
 * @throws ApiException If fail to serialize the request body object
 */
public Request buildRequest(String path, String method, List<Pair> queryParams, List<Pair> collectionQueryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {
    updateParamsForAuth(authNames, queryParams, headerParams);

    final String url = buildUrl(path, queryParams, collectionQueryParams);
    final Request.Builder reqBuilder = new Request.Builder().url(url);
    processHeaderParams(headerParams, reqBuilder);

    String contentType = (String) headerParams.get("Content-Type");
    // ensuring a default content type
    if (contentType == null) {
        contentType = "application/json";
    }

    RequestBody reqBody;
    if (!HttpMethod.permitsRequestBody(method)) {
        reqBody = null;
    } else if ("application/x-www-form-urlencoded".equals(contentType)) {
        reqBody = buildRequestBodyFormEncoding(formParams);
    } else if ("multipart/form-data".equals(contentType)) {
        reqBody = buildRequestBodyMultipart(formParams);
    } else if (body == null) {
        if ("DELETE".equals(method)) {
            // allow calling DELETE without sending a request body
            reqBody = null;
        } else {
            // use an empty request body (for POST, PUT and PATCH)
            reqBody = RequestBody.create(MediaType.parse(contentType), "");
        }
    } else {
        reqBody = serialize(body, contentType);
    }

    Request request = null;

    if(progressRequestListener != null && reqBody != null) {
        ProgressRequestBody progressRequestBody = new ProgressRequestBody(reqBody, progressRequestListener);
        request = reqBuilder.method(method, progressRequestBody).build();
    } else {
        request = reqBuilder.method(method, reqBody).build();
    }

    return request;
}
 

/**
 * Build an HTTP request with the given options.
 *
 * @param path The sub-path of the HTTP URL
 * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
 * @param queryParams The query parameters
 * @param collectionQueryParams The collection query parameters
 * @param body The request body object
 * @param headerParams The header parameters
 * @param formParams The form parameters
 * @param authNames The authentications to apply
 * @param progressRequestListener Progress request listener
 * @return The HTTP request 
 * @throws ApiException If fail to serialize the request body object
 */
public Request buildRequest(String path, String method, List<Pair> queryParams, List<Pair> collectionQueryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {
    updateParamsForAuth(authNames, queryParams, headerParams);

    final String url = buildUrl(path, queryParams, collectionQueryParams);
    final Request.Builder reqBuilder = new Request.Builder().url(url);
    processHeaderParams(headerParams, reqBuilder);

    String contentType = (String) headerParams.get("Content-Type");
    // ensuring a default content type
    if (contentType == null) {
        contentType = "application/json";
    }

    RequestBody reqBody;
    if (!HttpMethod.permitsRequestBody(method)) {
        reqBody = null;
    } else if ("application/x-www-form-urlencoded".equals(contentType)) {
        reqBody = buildRequestBodyFormEncoding(formParams);
    } else if ("multipart/form-data".equals(contentType)) {
        reqBody = buildRequestBodyMultipart(formParams);
    } else if (body == null) {
        if ("DELETE".equals(method)) {
            // allow calling DELETE without sending a request body
            reqBody = null;
        } else {
            // use an empty request body (for POST, PUT and PATCH)
            reqBody = RequestBody.create(MediaType.parse(contentType), "");
        }
    } else {
        reqBody = serialize(body, contentType);
    }

    Request request = null;

    if(progressRequestListener != null && reqBody != null) {
        ProgressRequestBody progressRequestBody = new ProgressRequestBody(reqBody, progressRequestListener);
        request = reqBuilder.method(method, progressRequestBody).build();
    } else {
        request = reqBuilder.method(method, reqBody).build();
    }

    return request;
}
 

private HttpEngine newHttpEngine(String method, Connection connection,
    RetryableSink requestBody, Response priorResponse) {
  // OkHttp's Call API requires a placeholder body; the real body will be streamed separately.
  RequestBody placeholderBody = HttpMethod.requiresRequestBody(method)
      ? EMPTY_REQUEST_BODY
      : null;
  Request.Builder builder = new Request.Builder()
      .url(getURL())
      .method(method, placeholderBody);
  Headers headers = requestHeaders.build();
  for (int i = 0, size = headers.size(); i < size; i++) {
    builder.addHeader(headers.name(i), headers.value(i));
  }

  boolean bufferRequestBody = false;
  if (HttpMethod.permitsRequestBody(method)) {
    // Specify how the request body is terminated.
    if (fixedContentLength != -1) {
      builder.header("Content-Length", Long.toString(fixedContentLength));
    } else if (chunkLength > 0) {
      builder.header("Transfer-Encoding", "chunked");
    } else {
      bufferRequestBody = true;
    }

    // Add a content type for the request body, if one isn't already present.
    if (headers.get("Content-Type") == null) {
      builder.header("Content-Type", "application/x-www-form-urlencoded");
    }
  }

  if (headers.get("User-Agent") == null) {
    builder.header("User-Agent", defaultUserAgent());
  }

  Request request = builder.build();

  // If we're currently not using caches, make sure the engine's client doesn't have one.
  OkHttpClient engineClient = client;
  if (Internal.instance.internalCache(engineClient) != null && !getUseCaches()) {
    engineClient = client.clone().setCache(null);
  }

  return new HttpEngine(engineClient, request, bufferRequestBody, true, false, connection, null,
      requestBody, priorResponse);
}