feat(grpc): initialize default metadata

- rpc.definition, eg. 'hero.HeroService'
- rpc.method, eg. 'findOne'
- rpc.method.type, unary|server|client

packages/grpc/src/comsumer/clients.ts

@@ -9,7 +9,7 @@ import {
   Utils,
   ILogger,
 } from '@midwayjs/core';
-import { credentials, loadPackageDefinition } from '@grpc/grpc-js';
+import { credentials, loadPackageDefinition, Metadata } from '@grpc/grpc-js';
 import {
   DefaultConfig,
   IClientOptions,
@@ -71,6 +71,17 @@ export class GRPCClients extends Map {
           connectionService[methodName] = (
             clientOptions: IClientOptions = {}
           ) => {
+            if (clientOptions.metadata) {
+              const meta = new Metadata();
+              meta.merge(clientOptions.metadata);
+              clientOptions.metadata = meta;
+            }
+            else {
+              clientOptions.metadata = new Metadata();
+            }
+            clientOptions.metadata.set('rpc.definition', definition);
+            clientOptions.metadata.set('rpc.method', methodName);
+
             return this.getClientRequestImpl(
               connectionService,
               originMethod,
@@ -89,35 +100,47 @@ export class GRPCClients extends Map {
     return this.get(serviceName);
   }
 
-  getClientRequestImpl(client, originalFunction, options = {}) {
+  getClientRequestImpl(client, originalFunction, options: IClientOptions = {}) {
     const genericFunctionSelector =
       (originalFunction.requestStream ? 2 : 0) |
       (originalFunction.responseStream ? 1 : 0);
 
+    if (options.metadata) {
+      const meta = new Metadata();
+      meta.merge(options.metadata);
+      options.metadata = meta;
+    } else {
+      options.metadata = new Metadata();
+    }
+
     let genericFunctionName;
     switch (genericFunctionSelector) {
       case 0:
+        options.metadata.set('rpc.method.type', 'unary');
         genericFunctionName = new ClientUnaryRequest(
           client,
           originalFunction,
           options
         );
         break;
       case 1:
+        options.metadata.set('rpc.method.type', 'server'); // server streaming
         genericFunctionName = new ClientReadableRequest(
           client,
           originalFunction,
           options
         );
         break;
       case 2:
+        options.metadata.set('rpc.method.type', 'client'); // client streaming
         genericFunctionName = new ClientWritableRequest(
           client,
           originalFunction,
           options
         );
         break;
       case 3:
+        options.metadata.set('rpc.method.type', 'bidi'); // bidirectional streaming
         genericFunctionName = new ClientDuplexStreamRequest(
           client,
           originalFunction,