Add arg builder support to putObject api (minio#972)

Author: balamurugana

api/src/main/java/io/minio/DownloadObjectArgs.java

@@ -21,31 +21,31 @@
 import java.nio.file.Paths;
 
 public class DownloadObjectArgs extends ObjectReadArgs {
-  private String fileName;
+  private String filename;
 
-  public String fileName() {
-    return fileName;
+  public String filename() {
+    return filename;
   }
 
   public static Builder builder() {
     return new Builder();
   }
 
   public static final class Builder extends ObjectReadArgs.Builder<Builder, DownloadObjectArgs> {
-    public Builder fileName(String fileName) {
-      validateFileName(fileName);
-      operations.add(args -> args.fileName = fileName);
+    public Builder filename(String filename) {
+      validateFileName(filename);
+      operations.add(args -> args.filename = filename);
       return this;
     }
 
-    private void validateFileName(String fileName) {
-      validateNotEmptyString(fileName, "filename");
+    private void validateFileName(String filename) {
+      validateNotEmptyString(filename, "filename");
 
-      Path filePath = Paths.get(fileName);
+      Path filePath = Paths.get(filename);
       boolean fileExists = Files.exists(filePath);
 
       if (fileExists && !Files.isRegularFile(filePath)) {
-        throw new IllegalArgumentException(fileName + ": not a regular file");
+        throw new IllegalArgumentException(filename + ": not a regular file");
       }
     }
   }

api/src/main/java/io/minio/GenericResponse.java

@@ -0,0 +1,32 @@
+/*
+ * MinIO Java SDK for Amazon S3 Compatible Cloud Storage, (C) 2020 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.minio;
+
+import okhttp3.Headers;
+
+/** Generic response class of any APIs. */
+public abstract class GenericResponse {
+  private Headers headers;
+
+  protected void setHeaders(Headers headers) {
+    this.headers = headers;
+  }
+
+  public Headers headers() {
+    return headers;
+  }
+}