fix: Fix mixin mock service and gradle build generation (#1010)

1) The generated mixin mock service classes must be in the same package as the service itself (not of the mixed-in service) - this is a regression of migrating to microgenerator. For example the PR when this happened for KMS: https://github.com/googleapis/java-kms/pull/502/files#diff-59a3127359a0458dedfaa9b6bdfc658e88a2491a6d907f32e17fac462b1a3c27L16

2) In case there is a location mixin, we also need to include grpc-google-common-protos dependency for output to compile

gapic-generator-java/rules_java_gapic/java_gapic_pkg.bzl

@@ -131,6 +131,7 @@ def _construct_extra_deps(scope_to_deps, versions_map):
         "iam_java_proto": "maven.com_google_api_grpc_proto_google_iam_v1",
         "iam_java_grpc": "maven.com_google_api_grpc_grpc_google_iam_v1",
         "iam_policy_java_grpc": "maven.com_google_api_grpc_grpc_google_iam_v1",
+        "location_java_grpc": "maven.com_google_api_grpc_grpc_google_common_protos",
     }
     extra_deps = {}
     for scope, deps in scope_to_deps.items():

gapic-generator-java/src/main/java/com/google/api/generator/gapic/protoparser/Parser.java

@@ -203,7 +203,12 @@ public static GapicContext parse(CodeGeneratorRequest request) {
 
     return GapicContext.builder()
         .setServices(services)
-        .setMixinServices(mixinServices)
+        .setMixinServices(
+            // Mixin classes must share the package with the service they are mixed in, instead of
+            // their original package
+            mixinServices.stream()
+                .map(s -> s.toBuilder().setPakkage(services.get(0).pakkage()).build())
+                .collect(Collectors.toList()))
         .setMessages(messages)
         .setResourceNames(resourceNames)
         .setHelperResourceNames(outputArgResourceNames)

gapic-generator-java/test/integration/goldens/kms/src/com/google/cloud/kms/v1/KeyManagementServiceClientTest.java

@@ -34,12 +34,10 @@
 import com.google.cloud.location.ListLocationsRequest;
 import com.google.cloud.location.ListLocationsResponse;
 import com.google.cloud.location.Location;
-import com.google.cloud.location.MockLocations;
 import com.google.common.collect.Lists;
 import com.google.iam.v1.Binding;
 import com.google.iam.v1.GetIamPolicyRequest;
 import com.google.iam.v1.GetPolicyOptions;
-import com.google.iam.v1.MockIAMPolicy;
 import com.google.iam.v1.Policy;
 import com.google.iam.v1.TestIamPermissionsRequest;
 import com.google.iam.v1.TestIamPermissionsResponse;

gapic-generator-java/test/integration/goldens/kms/src/com/google/iam/v1/MockIAMPolicy.java → gapic-generator-java/test/integration/goldens/kms/src/com/google/cloud/kms/v1/MockIAMPolicy.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.google.iam.v1;
+package com.google.cloud.kms.v1;
 
 import com.google.api.core.BetaApi;
 import com.google.api.gax.grpc.testing.MockGrpcService;

gapic-generator-java/test/integration/goldens/kms/src/com/google/iam/v1/MockIAMPolicyImpl.java → gapic-generator-java/test/integration/goldens/kms/src/com/google/cloud/kms/v1/MockIAMPolicyImpl.java

@@ -14,10 +14,14 @@
  * limitations under the License.
  */
 
-package com.google.iam.v1;
+package com.google.cloud.kms.v1;
 
 import com.google.api.core.BetaApi;
+import com.google.iam.v1.GetIamPolicyRequest;
 import com.google.iam.v1.IAMPolicyGrpc.IAMPolicyImplBase;
+import com.google.iam.v1.Policy;
+import com.google.iam.v1.TestIamPermissionsRequest;
+import com.google.iam.v1.TestIamPermissionsResponse;
 import com.google.protobuf.AbstractMessage;
 import io.grpc.stub.StreamObserver;
 import java.util.ArrayList;

gapic-generator-java/test/integration/goldens/kms/src/com/google/cloud/location/MockLocations.java → gapic-generator-java/test/integration/goldens/kms/src/com/google/cloud/kms/v1/MockLocations.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package com.google.cloud.location;
+package com.google.cloud.kms.v1;
 
 import com.google.api.core.BetaApi;
 import com.google.api.gax.grpc.testing.MockGrpcService;

gapic-generator-java/test/integration/goldens/kms/src/com/google/cloud/location/MockLocationsImpl.java → gapic-generator-java/test/integration/goldens/kms/src/com/google/cloud/kms/v1/MockLocationsImpl.java

@@ -14,9 +14,13 @@
  * limitations under the License.
  */
 
-package com.google.cloud.location;
+package com.google.cloud.kms.v1;
 
 import com.google.api.core.BetaApi;
+import com.google.cloud.location.GetLocationRequest;
+import com.google.cloud.location.ListLocationsRequest;
+import com.google.cloud.location.ListLocationsResponse;
+import com.google.cloud.location.Location;
 import com.google.cloud.location.LocationsGrpc.LocationsImplBase;
 import com.google.protobuf.AbstractMessage;
 import io.grpc.stub.StreamObserver;