rls: sync latest rls protos from grpc-proto (grpc#8638)

rls/src/main/proto/grpc/lookup/v1/rls.proto

@@ -22,14 +22,6 @@ option java_package = "io.grpc.lookup.v1";
 option java_outer_classname = "RlsProto";
 
 message RouteLookupRequest {
-  // Full host name of the target server, e.g. firestore.googleapis.com.
-  // Only set for gRPC requests; HTTP requests must use key_map explicitly.
-  // Deprecated in favor of setting key_map keys with GrpcKeyBuilder.extra_keys.
-  string server = 1 [deprecated = true];
-  // Full path of the request, i.e. "/service/method".
-  // Only set for gRPC requests; HTTP requests must use key_map explicitly.
-  // Deprecated in favor of setting key_map keys with GrpcKeyBuilder.extra_keys.
-  string path = 2 [deprecated = true];
   // Target type allows the client to specify what kind of target format it
   // would like from RLS to allow it to find the regional server, e.g. "grpc".
   string target_type = 3;
@@ -41,8 +33,13 @@ message RouteLookupRequest {
   }
   // Reason for making this request.
   Reason reason = 5;
+  // For REASON_STALE, the header_data from the stale response, if any.
+  string stale_header_data = 6;
   // Map of key values extracted via key builders for the gRPC or HTTP request.
   map<string, string> key_map = 4;
+
+  reserved 1, 2;
+  reserved "server", "path";
 }
 
 message RouteLookupResponse {

rls/src/main/proto/grpc/lookup/v1/rls_config.proto

@@ -216,3 +216,10 @@ message RouteLookupConfig {
   reserved 10;
   reserved "request_processing_strategy";
 }
+
+// RouteLookupClusterSpecifier is used in xDS to represent a cluster specifier
+// plugin for RLS.
+message RouteLookupClusterSpecifier {
+  // The RLS config for this cluster specifier plugin instance.
+  RouteLookupConfig route_lookup_config = 1;
+}