[Fix] Correctly include query parameters for APIs whose request objects contain the body as a field (#401)

## What changes are proposed in this pull request?
The Databricks API spec has two different styles of APIs, those where
the request body is a field in the `Request` structure, and those where
the request body is said structure (not counting the parameters passed
via the URI path and query string). The former style of APIs was
incorrectly implemented, preventing such APIs from using any query
parameters.

Generally, the approach taken here is to move the construction of the
request object into the autogenerated `Impl` classes and providing a
fully materialized `Request` object to the `ApiClient`. To do so, we
expose the `<T> T execute(Request in, Target Class<T>)` method as
public.

Separately, I've removed the per-HTTP-method methods from `ApiClient`,
opting instead to use the singular `execute`, as they purely create more
maintenance burden for us and decrease the surface area we need to
maintain.

## How is this tested?
Added `AppsImplTest` to verify that the no_compute flag is included in
the request passed to the `ApiClient`.

Author: mgyucht

databricks-sdk-java/src/main/java/com/databricks/sdk/core/ApiClient.java

@@ -151,7 +151,7 @@ private ApiClient(Builder builder) {
     bodyLogger = new BodyLogger(mapper, 1024, debugTruncateBytes);
   }
 
-  private static <I> void setQuery(Request in, I entity) {
+  public static <I> void setQuery(Request in, I entity) {
     if (entity == null) {
       return;
     }
@@ -161,140 +161,33 @@ private static <I> void setQuery(Request in, I entity) {
     }
   }
 
-  private static <I> void setHeaders(Request in, Map<String, String> headers) {
-    if (headers == null) {
-      return;
-    }
-    for (Map.Entry<String, String> e : headers.entrySet()) {
-      in.withHeader(e.getKey(), e.getValue());
-    }
-  }
-
-  public <I, O> Collection<O> getCollection(
-      String path, I in, Class<O> element, Map<String, String> headers) {
+  public <O> Collection<O> getCollection(Request req, Class<O> element) {
     return withJavaType(
-        path,
-        in,
-        mapper.getTypeFactory().constructCollectionType(Collection.class, element),
-        headers);
+        req, mapper.getTypeFactory().constructCollectionType(Collection.class, element));
   }
 
-  public <I> Map<String, String> getStringMap(String path, I in, Map<String, String> headers) {
+  public Map<String, String> getStringMap(Request req) {
     return withJavaType(
-        path,
-        in,
-        mapper.getTypeFactory().constructMapType(Map.class, String.class, String.class),
-        headers);
+        req, mapper.getTypeFactory().constructMapType(Map.class, String.class, String.class));
   }
 
-  protected <I, O> O withJavaType(
-      String path, I in, JavaType javaType, Map<String, String> headers) {
+  protected <I, O> O withJavaType(Request request, JavaType javaType) {
     try {
-      Request request = prepareRequest("GET", path, in, headers);
       Response response = getResponse(request);
       return deserialize(response.getBody(), javaType);
     } catch (IOException e) {
       throw new DatabricksException("IO error: " + e.getMessage(), e);
     }
   }
 
-  public <O> O HEAD(String path, Class<O> target, Map<String, String> headers) {
-    return HEAD(path, null, target, headers);
-  }
-
-  public <I, O> O HEAD(String path, I in, Class<O> target, Map<String, String> headers) {
-    try {
-      return execute(prepareRequest("HEAD", path, in, headers), target);
-    } catch (IOException e) {
-      throw new DatabricksException("IO error: " + e.getMessage(), e);
-    }
-  }
-
-  public <O> O GET(String path, Class<O> target, Map<String, String> headers) {
-    return GET(path, null, target, headers);
-  }
-
-  public <I, O> O GET(String path, I in, Class<O> target, Map<String, String> headers) {
-    try {
-      return execute(prepareRequest("GET", path, in, headers), target);
-    } catch (IOException e) {
-      throw new DatabricksException("IO error: " + e.getMessage(), e);
-    }
-  }
-
-  public <O> O POST(String path, Class<O> target, Map<String, String> headers) {
-    try {
-      return execute(prepareRequest("POST", path, null, headers), target);
-    } catch (IOException e) {
-      throw new DatabricksException("IO error: " + e.getMessage(), e);
-    }
-  }
-
-  public <I, O> O POST(String path, I in, Class<O> target, Map<String, String> headers) {
-    try {
-      return execute(prepareRequest("POST", path, in, headers), target);
-    } catch (IOException e) {
-      throw new DatabricksException("IO error: " + e.getMessage(), e);
-    }
-  }
-
-  public <I, O> O PUT(String path, I in, Class<O> target, Map<String, String> headers) {
-    try {
-      return execute(prepareRequest("PUT", path, in, headers), target);
-    } catch (IOException e) {
-      throw new DatabricksException("IO error: " + e.getMessage(), e);
-    }
-  }
-
-  public <I, O> O PATCH(String path, I in, Class<O> target, Map<String, String> headers) {
-    try {
-      return execute(prepareRequest("PATCH", path, in, headers), target);
-    } catch (IOException e) {
-      throw new DatabricksException("IO error: " + e.getMessage(), e);
-    }
-  }
-
-  public <I, O> O DELETE(String path, I in, Class<O> target, Map<String, String> headers) {
-    try {
-      return execute(prepareRequest("DELETE", path, in, headers), target);
-    } catch (IOException e) {
-      throw new DatabricksException("IO error: " + e.getMessage(), e);
-    }
-  }
-
-  private boolean hasBody(String method) {
-    return !method.equals("GET") && !method.equals("DELETE") && !method.equals("HEAD");
-  }
-
-  private <I> Request prepareBaseRequest(String method, String path, I in)
-      throws JsonProcessingException {
-    if (in == null || !hasBody(method)) {
-      return new Request(method, path);
-    } else if (InputStream.class.isAssignableFrom(in.getClass())) {
-      InputStream body = (InputStream) in;
-      return new Request(method, path, body);
-    } else {
-      String body = (in instanceof String) ? (String) in : serialize(in);
-      return new Request(method, path, body);
-    }
-  }
-
-  private <I> Request prepareRequest(String method, String path, I in, Map<String, String> headers)
-      throws JsonProcessingException {
-    Request req = prepareBaseRequest(method, path, in);
-    setQuery(req, in);
-    setHeaders(req, headers);
-    return req;
-  }
-
   /**
    * Executes HTTP request with retries and converts it to proper POJO
    *
    * @param in Commons HTTP request
    * @param target Expected pojo type
    * @return POJO of requested type
    */
-  private <T> T execute(Request in, Class<T> target) throws IOException {
+  public <T> T execute(Request in, Class<T> target) throws IOException {
     Response out = getResponse(in);
     if (target == Void.class) {
       return null;
@@ -533,7 +426,7 @@ public <T> void deserialize(Response response, T object) throws IOException {
     }
   }
 
-  private String serialize(Object body) throws JsonProcessingException {
+  public String serialize(Object body) throws JsonProcessingException {
     if (body == null) {
       return null;
     }

databricks-sdk-java/src/main/java/com/databricks/sdk/core/DatabricksConfig.java

@@ -586,10 +586,13 @@ private OpenIDConnectEndpoints fetchDefaultOidcEndpoints() throws IOException {
             .withHttpClient(getHttpClient())
             .withGetHostFunc(v -> getHost())
             .build();
-    return apiClient.GET(
-        "/oidc/.well-known/oauth-authorization-server",
-        OpenIDConnectEndpoints.class,
-        new HashMap<>());
+    try {
+      return apiClient.execute(
+          new Request("GET", "/oidc/.well-known/oauth-authorization-server"),
+          OpenIDConnectEndpoints.class);
+    } catch (IOException e) {
+      throw new DatabricksException("IO error: " + e.getMessage(), e);
+    }
   }
 
   @Override

databricks-sdk-java/src/main/java/com/databricks/sdk/core/oauth/RefreshableTokenSource.java

@@ -4,6 +4,7 @@
 import com.databricks.sdk.core.DatabricksException;
 import com.databricks.sdk.core.http.FormRequest;
 import com.databricks.sdk.core.http.HttpClient;
+import com.databricks.sdk.core.http.Request;
 import java.time.LocalDateTime;
 import java.time.temporal.ChronoUnit;
 import java.util.Base64;
@@ -61,12 +62,11 @@ protected static Token retrieveToken(
         break;
     }
     headers.put("Content-Type", "application/x-www-form-urlencoded");
+    Request req = new Request("POST", tokenUrl, FormRequest.wrapValuesInList(params));
+    req.withHeaders(headers);
     try {
       ApiClient apiClient = new ApiClient.Builder().withHttpClient(hc).build();
-
-      OAuthResponse resp =
-          apiClient.POST(
-              tokenUrl, FormRequest.wrapValuesInList(params), OAuthResponse.class, headers);
+      OAuthResponse resp = apiClient.execute(req, OAuthResponse.class);
       if (resp.getErrorCode() != null) {
         throw new IllegalArgumentException(resp.getErrorCode() + ": " + resp.getErrorSummary());
       }