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+// Copyright 2018 Google LLC
+// Modififications (C) 2018, Open Networking Foundation
+//
+// 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.
+
+// NOTE: On the provenance of and modifications to http.proto and
+// annotations.proto
+//
+// TL;DR: The files http.proto and annotations.proto are originally from here:
+//  https://github.com/googleapis/googleapis
+// They have been modified slightly to avoid a namespace conflict.
+//
+// Long winded explanation:
+// These files are designed to interact with Google's first party API's, and
+// the recommended way to use them is to compiled them to code with protoc and
+// included in your codebase before being used.  Due to the fact that we're not
+// using them that way, and because of how Chameleon and XOS work (dynamically
+// defining our own API's), we have to ship these *.proto files as a part of
+// our artifacts.
+//
+// The problems start when you try to include these specific .proto files in
+// python. The protoc compiler includes the `google.protobuf` classes, which
+// python can look up in the standard python library path. Unfortunately these
+// files are namespaced with `google.api` in the path and aren't shipped with
+// protoc.  This leads to a path conflict - you can't have two library paths
+// start with the same path component (`google` in this case) without getting
+// an "ImportError: No module named ..." on one of the paths when you import
+// them.
+//
+// Historically, various confusing hacks were implemented to override and
+// special-case the python `include` directive to include a file at a different
+// path than was specified. These hacks also failed when updating the base OS,
+// and would likely continue to fail in other, stranger ways as we update the
+// codebase.  Specifically, Python 3 reimplemented these features in the
+// importlib section of the standard library, so there's little confidence our
+// hacks would continue to work.  As an aside, there are various protobuf
+// `options` statements to deal with this sort of issue in other languages (see
+// the `go_package` and `java_package` below ) but these don't currently exist
+// for python: https://github.com/google/protobuf/issues/973
+//
+// To avoid this entire psychotic namespace hellscape, it's much easier to
+// modify these files to remove the google.api path component, and have them
+// included directly at a path of our own choice.
+
+syntax = "proto3";
+
+package googleapi;
+
+option cc_enable_arenas = true;
+option go_package = "google.golang.org/genproto/googleapis/api/annotations;annotations";
+option java_multiple_files = true;
+option java_outer_classname = "HttpProto";
+option java_package = "com.google.api";
+option objc_class_prefix = "GAPI";
+
+
+// Defines the HTTP configuration for an API service. It contains a list of
+// [HttpRule][google.api.HttpRule], each specifying the mapping of an RPC method
+// to one or more HTTP REST API methods.
+message Http {
+  // A list of HTTP configuration rules that apply to individual API methods.
+  //
+  // **NOTE:** All service configuration rules follow "last one wins" order.
+  repeated HttpRule rules = 1;
+
+  // When set to true, URL path parmeters will be fully URI-decoded except in
+  // cases of single segment matches in reserved expansion, where "%2F" will be
+  // left encoded.
+  //
+  // The default behavior is to not decode RFC 6570 reserved characters in multi
+  // segment matches.
+  bool fully_decode_reserved_expansion = 2;
+}
+
+// `HttpRule` defines the mapping of an RPC method to one or more HTTP
+// REST API methods. The mapping specifies how different portions of the RPC
+// request message are mapped to URL path, URL query parameters, and
+// HTTP request body. The mapping is typically specified as an
+// `google.api.http` annotation on the RPC method,
+// see "google/api/annotations.proto" for details.
+//
+// The mapping consists of a field specifying the path template and
+// method kind.  The path template can refer to fields in the request
+// message, as in the example below which describes a REST GET
+// operation on a resource collection of messages:
+//
+//
+//     service Messaging {
+//       rpc GetMessage(GetMessageRequest) returns (Message) {
+//         option (google.api.http).get = "/v1/messages/{message_id}/{sub.subfield}";
+//       }
+//     }
+//     message GetMessageRequest {
+//       message SubMessage {
+//         string subfield = 1;
+//       }
+//       string message_id = 1; // mapped to the URL
+//       SubMessage sub = 2;    // `sub.subfield` is url-mapped
+//     }
+//     message Message {
+//       string text = 1; // content of the resource
+//     }
+//
+// The same http annotation can alternatively be expressed inside the
+// `GRPC API Configuration` YAML file.
+//
+//     http:
+//       rules:
+//         - selector: <proto_package_name>.Messaging.GetMessage
+//           get: /v1/messages/{message_id}/{sub.subfield}
+//
+// This definition enables an automatic, bidrectional mapping of HTTP
+// JSON to RPC. Example:
+//
+// HTTP | RPC
+// -----|-----
+// `GET /v1/messages/123456/foo`  | `GetMessage(message_id: "123456" sub: SubMessage(subfield: "foo"))`
+//
+// In general, not only fields but also field paths can be referenced
+// from a path pattern. Fields mapped to the path pattern cannot be
+// repeated and must have a primitive (non-message) type.
+//
+// Any fields in the request message which are not bound by the path
+// pattern automatically become (optional) HTTP query
+// parameters. Assume the following definition of the request message:
+//
+//
+//     service Messaging {
+//       rpc GetMessage(GetMessageRequest) returns (Message) {
+//         option (google.api.http).get = "/v1/messages/{message_id}";
+//       }
+//     }
+//     message GetMessageRequest {
+//       message SubMessage {
+//         string subfield = 1;
+//       }
+//       string message_id = 1; // mapped to the URL
+//       int64 revision = 2;    // becomes a parameter
+//       SubMessage sub = 3;    // `sub.subfield` becomes a parameter
+//     }
+//
+//
+// This enables a HTTP JSON to RPC mapping as below:
+//
+// HTTP | RPC
+// -----|-----
+// `GET /v1/messages/123456?revision=2&sub.subfield=foo` | `GetMessage(message_id: "123456" revision: 2 sub: SubMessage(subfield: "foo"))`
+//
+// Note that fields which are mapped to HTTP parameters must have a
+// primitive type or a repeated primitive type. Message types are not
+// allowed. In the case of a repeated type, the parameter can be
+// repeated in the URL, as in `...?param=A&param=B`.
+//
+// For HTTP method kinds which allow a request body, the `body` field
+// specifies the mapping. Consider a REST update method on the
+// message resource collection:
+//
+//
+//     service Messaging {
+//       rpc UpdateMessage(UpdateMessageRequest) returns (Message) {
+//         option (google.api.http) = {
+//           put: "/v1/messages/{message_id}"
+//           body: "message"
+//         };
+//       }
+//     }
+//     message UpdateMessageRequest {
+//       string message_id = 1; // mapped to the URL
+//       Message message = 2;   // mapped to the body
+//     }
+//
+//
+// The following HTTP JSON to RPC mapping is enabled, where the
+// representation of the JSON in the request body is determined by
+// protos JSON encoding:
+//
+// HTTP | RPC
+// -----|-----
+// `PUT /v1/messages/123456 { "text": "Hi!" }` | `UpdateMessage(message_id: "123456" message { text: "Hi!" })`
+//
+// The special name `*` can be used in the body mapping to define that
+// every field not bound by the path template should be mapped to the
+// request body.  This enables the following alternative definition of
+// the update method:
+//
+//     service Messaging {
+//       rpc UpdateMessage(Message) returns (Message) {
+//         option (google.api.http) = {
+//           put: "/v1/messages/{message_id}"
+//           body: "*"
+//         };
+//       }
+//     }
+//     message Message {
+//       string message_id = 1;
+//       string text = 2;
+//     }
+//
+//
+// The following HTTP JSON to RPC mapping is enabled:
+//
+// HTTP | RPC
+// -----|-----
+// `PUT /v1/messages/123456 { "text": "Hi!" }` | `UpdateMessage(message_id: "123456" text: "Hi!")`
+//
+// Note that when using `*` in the body mapping, it is not possible to
+// have HTTP parameters, as all fields not bound by the path end in
+// the body. This makes this option more rarely used in practice of
+// defining REST APIs. The common usage of `*` is in custom methods
+// which don't use the URL at all for transferring data.
+//
+// It is possible to define multiple HTTP methods for one RPC by using
+// the `additional_bindings` option. Example:
+//
+//     service Messaging {
+//       rpc GetMessage(GetMessageRequest) returns (Message) {
+//         option (google.api.http) = {
+//           get: "/v1/messages/{message_id}"
+//           additional_bindings {
+//             get: "/v1/users/{user_id}/messages/{message_id}"
+//           }
+//         };
+//       }
+//     }
+//     message GetMessageRequest {
+//       string message_id = 1;
+//       string user_id = 2;
+//     }
+//
+//
+// This enables the following two alternative HTTP JSON to RPC
+// mappings:
+//
+// HTTP | RPC
+// -----|-----
+// `GET /v1/messages/123456` | `GetMessage(message_id: "123456")`
+// `GET /v1/users/me/messages/123456` | `GetMessage(user_id: "me" message_id: "123456")`
+//
+// # Rules for HTTP mapping
+//
+// The rules for mapping HTTP path, query parameters, and body fields
+// to the request message are as follows:
+//
+// 1. The `body` field specifies either `*` or a field path, or is
+//    omitted. If omitted, it indicates there is no HTTP request body.
+// 2. Leaf fields (recursive expansion of nested messages in the
+//    request) can be classified into three types:
+//     (a) Matched in the URL template.
+//     (b) Covered by body (if body is `*`, everything except (a) fields;
+//         else everything under the body field)
+//     (c) All other fields.
+// 3. URL query parameters found in the HTTP request are mapped to (c) fields.
+// 4. Any body sent with an HTTP request can contain only (b) fields.
+//
+// The syntax of the path template is as follows:
+//
+//     Template = "/" Segments [ Verb ] ;
+//     Segments = Segment { "/" Segment } ;
+//     Segment  = "*" | "**" | LITERAL | Variable ;
+//     Variable = "{" FieldPath [ "=" Segments ] "}" ;
+//     FieldPath = IDENT { "." IDENT } ;
+//     Verb     = ":" LITERAL ;
+//
+// The syntax `*` matches a single path segment. The syntax `**` matches zero
+// or more path segments, which must be the last part of the path except the
+// `Verb`. The syntax `LITERAL` matches literal text in the path.
+//
+// The syntax `Variable` matches part of the URL path as specified by its
+// template. A variable template must not contain other variables. If a variable
+// matches a single path segment, its template may be omitted, e.g. `{var}`
+// is equivalent to `{var=*}`.
+//
+// If a variable contains exactly one path segment, such as `"{var}"` or
+// `"{var=*}"`, when such a variable is expanded into a URL path, all characters
+// except `[-_.~0-9a-zA-Z]` are percent-encoded. Such variables show up in the
+// Discovery Document as `{var}`.
+//
+// If a variable contains one or more path segments, such as `"{var=foo/*}"`
+// or `"{var=**}"`, when such a variable is expanded into a URL path, all
+// characters except `[-_.~/0-9a-zA-Z]` are percent-encoded. Such variables
+// show up in the Discovery Document as `{+var}`.
+//
+// NOTE: While the single segment variable matches the semantics of
+// [RFC 6570](https://tools.ietf.org/html/rfc6570) Section 3.2.2
+// Simple String Expansion, the multi segment variable **does not** match
+// RFC 6570 Reserved Expansion. The reason is that the Reserved Expansion
+// does not expand special characters like `?` and `#`, which would lead
+// to invalid URLs.
+//
+// NOTE: the field paths in variables and in the `body` must not refer to
+// repeated fields or map fields.
+message HttpRule {
+  // Selects methods to which this rule applies.
+  //
+  // Refer to [selector][google.api.DocumentationRule.selector] for syntax details.
+  string selector = 1;
+
+  // Determines the URL pattern is matched by this rules. This pattern can be
+  // used with any of the {get|put|post|delete|patch} methods. A custom method
+  // can be defined using the 'custom' field.
+  oneof pattern {
+    // Used for listing and getting information about resources.
+    string get = 2;
+
+    // Used for updating a resource.
+    string put = 3;
+
+    // Used for creating a resource.
+    string post = 4;
+
+    // Used for deleting a resource.
+    string delete = 5;
+
+    // Used for updating a resource.
+    string patch = 6;
+
+    // The custom pattern is used for specifying an HTTP method that is not
+    // included in the `pattern` field, such as HEAD, or "*" to leave the
+    // HTTP method unspecified for this rule. The wild-card rule is useful
+    // for services that provide content to Web (HTML) clients.
+    CustomHttpPattern custom = 8;
+  }
+
+  // The name of the request field whose value is mapped to the HTTP body, or
+  // `*` for mapping all fields not captured by the path pattern to the HTTP
+  // body. NOTE: the referred field must not be a repeated field and must be
+  // present at the top-level of request message type.
+  string body = 7;
+
+  // Additional HTTP bindings for the selector. Nested bindings must
+  // not contain an `additional_bindings` field themselves (that is,
+  // the nesting may only be one level deep).
+  repeated HttpRule additional_bindings = 11;
+}
+
+// A custom pattern is used for defining custom HTTP verb.
+message CustomHttpPattern {
+  // The name of this custom HTTP verb.
+  string kind = 1;
+
+  // The path matched by this custom verb.
+  string path = 2;
+}