Use oneof for the two options

cs3/storage/provider/v1beta1/provider_api.proto

@@ -280,18 +280,20 @@ message InitiateFileUploadRequest {
   // REQUIRED.
   // The reference to which the action should be performed.
   Reference ref = 2;
-  // OPTIONAL.
-  // Whether the file is to be uploaded in exclusive mode. Defaults to false.
-  // If true, the request SHALL be processed such that only one of multiple concurrent uploads
-  // to the same target reference MAY succeed, whereas all others MUST fail with CODE_ALREADY_EXISTS.
-  // The semantic is similar to the O_CREAT|O_EXCL POSIX flags.
-  // The request MUST return CODE_NOT_IMPLEMENTED if the provider does not support this mode.
-  bool if_not_exist = 3;
-  // OPTIONAL.
-  // Whether the file is to be uploaded if the given etag matches. Default to always upload.
-  // If a mismatching etag is given, the request MUST return CODE_ALREADY_EXISTS with the current etag
-  // in the opaque field.
-  string if_match = 4;
+  oneof options {
+    // OPTIONAL.
+    // Whether the file is to be uploaded in exclusive mode. Defaults to false.
+    // If true, the request SHALL be processed such that only one of multiple concurrent uploads
+    // to the same target reference MAY succeed, whereas all others MUST fail with CODE_ALREADY_EXISTS.
+    // The semantic is similar to the O_CREAT|O_EXCL POSIX flags.
+    // The request MUST return CODE_NOT_IMPLEMENTED if the provider does not support this mode.
+    bool if_not_exist = 3;
+    // OPTIONAL.
+    // Whether the file is to be uploaded if the given etag matches. Default to always upload.
+    // If a mismatching etag is given, the request MUST return CODE_ALREADY_EXISTS with the current etag
+    // in the opaque field.
+    string if_match = 4;
+  }
 }
 
 message InitiateFileUploadResponse {