Remove unnecessary imports and superfluous type checks (#525)

example/helloworld/bin/client.dart

@@ -15,7 +15,6 @@
 
 /// Dart implementation of the gRPC helloworld.Greeter client.
 import 'package:grpc/grpc.dart';
-import 'package:helloworld/src/generated/helloworld.pb.dart';
 import 'package:helloworld/src/generated/helloworld.pbgrpc.dart';
 
 Future<void> main(List<String> args) async {

example/helloworld/bin/server.dart

@@ -15,7 +15,6 @@
 
 /// Dart implementation of the gRPC helloworld.Greeter server.
 import 'package:grpc/grpc.dart';
-import 'package:helloworld/src/generated/helloworld.pb.dart';
 import 'package:helloworld/src/generated/helloworld.pbgrpc.dart';
 
 class GreeterService extends GreeterServiceBase {

example/helloworld/bin/unix_client.dart

@@ -15,9 +15,8 @@
 
 /// Dart implementation of the gRPC helloworld.Greeter client.
 import 'dart:io';
-import 'package:grpc/grpc.dart';
 
-import 'package:helloworld/src/generated/helloworld.pb.dart';
+import 'package:grpc/grpc.dart';
 import 'package:helloworld/src/generated/helloworld.pbgrpc.dart';
 
 Future<void> main(List<String> args) async {

example/helloworld/bin/unix_server.dart

@@ -15,9 +15,8 @@
 
 /// Dart implementation of the gRPC helloworld.Greeter server.
 import 'dart:io';
-import 'package:grpc/grpc.dart';
 
-import 'package:helloworld/src/generated/helloworld.pb.dart';
+import 'package:grpc/grpc.dart';
 import 'package:helloworld/src/generated/helloworld.pbgrpc.dart';
 
 class GreeterService extends GreeterServiceBase {

example/route_guide/lib/src/client.dart

@@ -18,7 +18,6 @@ import 'dart:math' show Random;
 import 'package:grpc/grpc.dart';
 
 import 'common.dart';
-import 'generated/route_guide.pb.dart';
 import 'generated/route_guide.pbgrpc.dart';
 
 class Client {

example/route_guide/lib/src/server.dart

@@ -18,7 +18,6 @@ import 'dart:math' show atan2, cos, max, min, pi, sin, sqrt;
 import 'package:grpc/grpc.dart' as grpc;
 
 import 'common.dart';
-import 'generated/route_guide.pb.dart';
 import 'generated/route_guide.pbgrpc.dart';
 
 class RouteGuideService extends RouteGuideServiceBase {

interop/lib/src/client.dart

@@ -19,6 +19,7 @@ import 'dart:typed_data';
 
 import 'package:collection/collection.dart';
 import 'package:grpc/grpc.dart';
+
 import 'generated/empty.pb.dart';
 import 'generated/messages.pb.dart';
 import 'generated/test.pbgrpc.dart';
@@ -152,8 +153,7 @@ class Tester {
   /// * call was successful
   /// * response is non-null
   Future<void> emptyUnary() async {
-    final response = await client.emptyCall(Empty());
-    if (response is! Empty) throw 'Expected Empty response.';
+    await client.emptyCall(Empty());
   }
 
   /// This test verifies that gRPC requests marked as cacheable use GET verb

test/client_handles_bad_connections_test.dart

@@ -1,12 +1,13 @@
 @TestOn('vm')
 import 'dart:async';
+
 import 'package:grpc/grpc.dart' as grpc;
-import 'package:grpc/service_api.dart';
 import 'package:grpc/src/client/channel.dart';
 import 'package:grpc/src/client/connection.dart';
 import 'package:grpc/src/client/http2_connection.dart';
 import 'package:http2/http2.dart';
 import 'package:test/test.dart';
+
 import 'common.dart';
 
 class TestClient extends grpc.Client {

test/client_tests/client_interceptor_test.dart

@@ -1,7 +1,6 @@
 import 'dart:async';
 
 import 'package:grpc/grpc.dart';
-import 'package:grpc/src/client/interceptor.dart';
 import 'package:http2/transport.dart';
 import 'package:test/test.dart';
 

test/client_tests/client_test.dart

@@ -18,7 +18,6 @@ import 'dart:convert';
 import 'dart:io' show HttpStatus;
 
 import 'package:grpc/grpc.dart';
-import 'package:grpc/src/client/call.dart';
 import 'package:grpc/src/client/http2_connection.dart';
 import 'package:grpc/src/generated/google/rpc/status.pb.dart';
 import 'package:grpc/src/shared/status.dart';

test/client_tests/grpc_or_grpcweb_channel_grpc_test.dart

@@ -13,7 +13,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 @TestOn('!browser')
-
 import 'package:grpc/grpc.dart';
 import 'package:grpc/grpc_or_grpcweb.dart';
 import 'package:test/test.dart';
@@ -28,7 +27,6 @@ void main() {
       port: port,
       transportSecure: false,
     );
-    expect(channel is ClientChannel, isTrue);
     expect(channel.host, equals(host));
     expect(channel.port, equals(port));
     expect(channel.options.credentials.isSecure, isFalse);