[ggj][resnames][codegen] fix: add default value fallback for wildcard-only resnames (#562)

* feat: add parsing for language_settings in gapic.yaml

* fix: restructure GapicServiceConfig table-processing into ctor

* fix: refactor {LRO,Batching} settings out of GapicServiceConfig's required creation params

* build: support file deletion in integration test update Bazel rules

* feat: support gapic.yaml Java name overrides for Service{Client,Settings}

* fix: use gapic.yaml override names in comments

* fix: Use the right file

* fix: add default value fallback for wildcard-only resnames

Author: miraleung

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

@@ -65,7 +65,9 @@ static Expr createDefaultValue(
               "No resource name found for reference %s",
               methodArg.field().resourceReference().resourceTypeString()));
       return createDefaultValue(
-          resourceName, resourceNames.values().stream().collect(Collectors.toList()));
+          resourceName,
+          resourceNames.values().stream().collect(Collectors.toList()),
+          methodArg.field().name());
     }
 
     if (methodArg.type().equals(methodArg.field().type())) {
@@ -150,7 +152,8 @@ static Expr createDefaultValue(Field f, boolean useExplicitInitTypeInGenerics) {
             "Default value for field %s with type %s not implemented yet.", f.name(), f.type()));
   }
 
-  static Expr createDefaultValue(ResourceName resourceName, List<ResourceName> resnames) {
+  static Expr createDefaultValue(
+      ResourceName resourceName, List<ResourceName> resnames, String fieldOrMessageName) {
     boolean hasOnePattern = resourceName.patterns().size() == 1;
     if (resourceName.isOnlyWildcard()) {
       List<ResourceName> unexaminedResnames = new ArrayList<>(resnames);
@@ -160,13 +163,14 @@ static Expr createDefaultValue(ResourceName resourceName, List<ResourceName> res
           continue;
         }
         unexaminedResnames.remove(resname);
-        return createDefaultValue(resname, unexaminedResnames);
+        return createDefaultValue(resname, unexaminedResnames, fieldOrMessageName);
+      }
+
+      if (unexaminedResnames.isEmpty()) {
+        return ValueExpr.withValue(
+            StringObjectValue.withValue(
+                String.format("%s%s", fieldOrMessageName, fieldOrMessageName.hashCode())));
       }
-      // Should not get here.
-      Preconditions.checkState(
-          !unexaminedResnames.isEmpty(),
-          String.format(
-              "No default resource name found for wildcard %s", resourceName.resourceTypeString()));
     }
 
     // The cost tradeoffs of new ctors versus distinct() don't really matter here, since this list
@@ -242,7 +246,8 @@ static Expr createSimpleMessageBuilderExpr(
         defaultExpr =
             createDefaultValue(
                 resourceNames.get(field.resourceReference().resourceTypeString()),
-                resourceNames.values().stream().collect(Collectors.toList()));
+                resourceNames.values().stream().collect(Collectors.toList()),
+                message.name());
         defaultExpr =
             MethodInvocationExpr.builder()
                 .setExprReferenceExpr(defaultExpr)

src/test/java/com/google/api/generator/gapic/composer/DefaultValueComposerTest.java

@@ -15,7 +15,6 @@
 package com.google.api.generator.gapic.composer;
 
 import static junit.framework.Assert.assertEquals;
-import static org.junit.Assert.assertThrows;
 
 import com.google.api.generator.engine.ast.ConcreteReference;
 import com.google.api.generator.engine.ast.Expr;
@@ -153,7 +152,8 @@ public void defaultValue_resourceNameWithOnePattern() {
     Expr expr =
         DefaultValueComposer.createDefaultValue(
             resourceName,
-            typeStringsToResourceNames.values().stream().collect(Collectors.toList()));
+            typeStringsToResourceNames.values().stream().collect(Collectors.toList()),
+            "ignored");
     expr.accept(writerVisitor);
     assertEquals("BillingAccountName.of(\"[BILLING_ACCOUNT]\")", writerVisitor.write());
   }
@@ -168,7 +168,8 @@ public void defaultValue_resourceNameWithMultiplePatterns() {
     Expr expr =
         DefaultValueComposer.createDefaultValue(
             resourceName,
-            typeStringsToResourceNames.values().stream().collect(Collectors.toList()));
+            typeStringsToResourceNames.values().stream().collect(Collectors.toList()),
+            "ignored");
     expr.accept(writerVisitor);
     assertEquals(
         "FolderName.ofProjectFolderName(\"[PROJECT]\", \"[FOLDER]\")", writerVisitor.write());
@@ -184,13 +185,14 @@ public void defaultValue_resourceNameWithWildcardPattern() {
     Expr expr =
         DefaultValueComposer.createDefaultValue(
             resourceName,
-            typeStringsToResourceNames.values().stream().collect(Collectors.toList()));
+            typeStringsToResourceNames.values().stream().collect(Collectors.toList()),
+            "ignored");
     expr.accept(writerVisitor);
     assertEquals("DocumentName.ofDocumentName(\"[DOCUMENT]\")", writerVisitor.write());
   }
 
   @Test
-  public void invalidDefaultValue_wildcardResourceNameWithOnlyDeletedTopic() {
+  public void defaultValue_wildcardResourceNameWithOnlyDeletedTopic() {
     // Edge case that should never happen in practice.
     // Wildcard, but the resource names map has only other names that contain only the deleted-topic
     // constant.
@@ -205,13 +207,14 @@ public void invalidDefaultValue_wildcardResourceNameWithOnlyDeletedTopic() {
     Expr expr =
         DefaultValueComposer.createDefaultValue(
             resourceName,
-            typeStringsToResourceNames.values().stream().collect(Collectors.toList()));
+            typeStringsToResourceNames.values().stream().collect(Collectors.toList()),
+            "ignored");
     expr.accept(writerVisitor);
     assertEquals("TopicName.ofDeletedTopic()", writerVisitor.write());
   }
 
   @Test
-  public void invalidDefaultValue_resourceNameWithOnlyWildcards() {
+  public void defaultValue_resourceNameWithOnlyWildcards() {
     // Edge case that should never happen in practice.
     // Wildcard, but the resource names map has only other names that contain only the deleted-topic
     // constant.
@@ -220,9 +223,13 @@ public void invalidDefaultValue_resourceNameWithOnlyWildcards() {
         Parser.parseResourceNames(lockerServiceFileDescriptor);
     ResourceName resourceName =
         typeStringsToResourceNames.get("cloudresourcemanager.googleapis.com/Anything");
-    assertThrows(
-        IllegalStateException.class,
-        () -> DefaultValueComposer.createDefaultValue(resourceName, Collections.emptyList()));
+    String fallbackField = "foobar";
+    Expr expr =
+        DefaultValueComposer.createDefaultValue(
+            resourceName, Collections.emptyList(), fallbackField);
+    expr.accept(writerVisitor);
+    assertEquals(
+        String.format("\"%s%s\"", fallbackField, fallbackField.hashCode()), writerVisitor.write());
   }
 
   @Test