[ggj][codegen] fix: generate param-less RPC Java methods for empty sigs

src/main/java/com/google/api/generator/gapic/composer/ServiceClientTestClassComposer.java

@@ -424,6 +424,7 @@ private static List<MethodDefinition> createTestMethods(
                 service,
                 Collections.emptyList(),
                 0,
+                true,
                 classMemberVarExprs,
                 resourceNames,
                 messageTypes));
@@ -444,6 +445,7 @@ private static List<MethodDefinition> createTestMethods(
                   service,
                   method.methodSignatures().get(i),
                   i,
+                  false,
                   classMemberVarExprs,
                   resourceNames,
                   messageTypes));
@@ -467,6 +469,7 @@ private static MethodDefinition createRpcTestMethod(
       Service service,
       List<MethodArgument> methodSignature,
       int variantIndex,
+      boolean isRequestArg,
       Map<String, VariableExpr> classMemberVarExprs,
       Map<String, ResourceName> resourceNames,
       Map<String, Message> messageTypes) {
@@ -584,7 +587,6 @@ private static MethodDefinition createRpcTestMethod(
     methodStatements.add(EMPTY_LINE_STATEMENT);
 
     // Construct the request or method arguments.
-    boolean isRequestArg = methodSignature.isEmpty();
     VariableExpr requestVarExpr = null;
     Message requestMessage = null;
     List<VariableExpr> argExprs = new ArrayList<>();

src/main/java/com/google/api/generator/gapic/protoparser/MethodSignatureParser.java

@@ -27,6 +27,7 @@
 import com.google.common.collect.Lists;
 import com.google.protobuf.Descriptors.MethodDescriptor;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -61,6 +62,7 @@ public static List<List<MethodArgument>> parseMethodSignatures(
     // stringSigs: ["content,error", "content,error,info"].
     for (String stringSig : stringSigs) {
       if (Strings.isNullOrEmpty(stringSig)) {
+        signatures.add(Collections.emptyList());
         continue;
       }
 

src/test/java/com/google/api/generator/gapic/composer/goldens/EchoClient.golden

@@ -143,6 +143,16 @@ public class EchoClient implements BackgroundResource {
     return operationsClient;
   }
 
+  // AUTO-GENERATED DOCUMENTATION AND METHOD.
+  /**
+   * @param request The request object containing all of the parameters for the API call.
+   * @throws com.google.api.gax.rpc.ApiException if the remote call fails
+   */
+  public final EchoResponse echo() {
+    EchoRequest request = EchoRequest.newBuilder().build();
+    return echo(request);
+  }
+
   // AUTO-GENERATED DOCUMENTATION AND METHOD.
   /**
    * @param parent
@@ -280,6 +290,38 @@ public class EchoClient implements BackgroundResource {
     return stub.pagedExpandCallable();
   }
 
+  // AUTO-GENERATED DOCUMENTATION AND METHOD.
+  /**
+   * @param request The request object containing all of the parameters for the API call.
+   * @throws com.google.api.gax.rpc.ApiException if the remote call fails
+   */
+  public final SimplePagedExpandPagedResponse simplePagedExpand() {
+    PagedExpandRequest request = PagedExpandRequest.newBuilder().build();
+    return simplePagedExpand(request);
+  }
+
+  // AUTO-GENERATED DOCUMENTATION AND METHOD.
+  /**
+   * @param request The request object containing all of the parameters for the API call.
+   * @throws com.google.api.gax.rpc.ApiException if the remote call fails
+   */
+  public final SimplePagedExpandPagedResponse simplePagedExpand(PagedExpandRequest request) {
+    return simplePagedExpandPagedCallable().call(request);
+  }
+
+  // AUTO-GENERATED DOCUMENTATION AND METHOD.
+  /** Sample code: */
+  public final UnaryCallable<PagedExpandRequest, SimplePagedExpandPagedResponse>
+      simplePagedExpandPagedCallable() {
+    return stub.simplePagedExpandPagedCallable();
+  }
+
+  // AUTO-GENERATED DOCUMENTATION AND METHOD.
+  /** Sample code: */
+  public final UnaryCallable<PagedExpandRequest, PagedExpandResponse> simplePagedExpandCallable() {
+    return stub.simplePagedExpandCallable();
+  }
+
   // AUTO-GENERATED DOCUMENTATION AND METHOD.
   /**
    * @param ttl
@@ -445,4 +487,86 @@ public class EchoClient implements BackgroundResource {
       return new PagedExpandFixedSizeCollection(pages, collectionSize);
     }
   }
+
+  public static class SimplePagedExpandPagedResponse
+      extends AbstractPagedListResponse<
+          PagedExpandRequest,
+          PagedExpandResponse,
+          EchoResponse,
+          SimplePagedExpandPage,
+          SimplePagedExpandFixedSizeCollection> {
+
+    public static ApiFuture<SimplePagedExpandPagedResponse> createAsync(
+        PageContext<PagedExpandRequest, PagedExpandResponse, EchoResponse> context,
+        ApiFuture<PagedExpandResponse> futureResponse) {
+      ApiFuture<SimplePagedExpandPage> futurePage =
+          SimplePagedExpandPage.createEmptyPage().createPageAsync(context, futureResponse);
+      return ApiFutures.transform(
+          futurePage,
+          new ApiFunction<SimplePagedExpandPage, SimplePagedExpandPagedResponse>() {
+            @Override
+            public SimplePagedExpandPagedResponse apply(SimplePagedExpandPage input) {
+              return new SimplePagedExpandPagedResponse(input);
+            }
+          },
+          MoreExecutors.directExecutor());
+    }
+
+    private SimplePagedExpandPagedResponse(SimplePagedExpandPage page) {
+      super(page, SimplePagedExpandFixedSizeCollection.createEmptyCollection());
+    }
+  }
+
+  public static class SimplePagedExpandPage
+      extends AbstractPage<
+          PagedExpandRequest, PagedExpandResponse, EchoResponse, SimplePagedExpandPage> {
+
+    private SimplePagedExpandPage(
+        PageContext<PagedExpandRequest, PagedExpandResponse, EchoResponse> context,
+        PagedExpandResponse response) {
+      super(context, response);
+    }
+
+    private static SimplePagedExpandPage createEmptyPage() {
+      return new SimplePagedExpandPage(null, null);
+    }
+
+    @Override
+    protected SimplePagedExpandPage createPage(
+        PageContext<PagedExpandRequest, PagedExpandResponse, EchoResponse> context,
+        PagedExpandResponse response) {
+      return new SimplePagedExpandPage(context, response);
+    }
+
+    @Override
+    public ApiFuture<SimplePagedExpandPage> createPageAsync(
+        PageContext<PagedExpandRequest, PagedExpandResponse, EchoResponse> context,
+        ApiFuture<PagedExpandResponse> futureResponse) {
+      return super.createPageAsync(context, futureResponse);
+    }
+  }
+
+  public static class SimplePagedExpandFixedSizeCollection
+      extends AbstractFixedSizeCollection<
+          PagedExpandRequest,
+          PagedExpandResponse,
+          EchoResponse,
+          SimplePagedExpandPage,
+          SimplePagedExpandFixedSizeCollection> {
+
+    private SimplePagedExpandFixedSizeCollection(
+        List<SimplePagedExpandPage> pages, int collectionSize) {
+      super(pages, collectionSize);
+    }
+
+    private static SimplePagedExpandFixedSizeCollection createEmptyCollection() {
+      return new SimplePagedExpandFixedSizeCollection(null, 0);
+    }
+
+    @Override
+    protected SimplePagedExpandFixedSizeCollection createCollection(
+        List<SimplePagedExpandPage> pages, int collectionSize) {
+      return new SimplePagedExpandFixedSizeCollection(pages, collectionSize);
+    }
+  }
 }