[ggj][engx] fix: consolidate findRepeatedField into Message

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

@@ -817,21 +817,15 @@ private static List<ClassDefinition> createNestedPagingClasses(
       }
       // Find the repeated field.
       Message methodOutputMessage = messageTypes.get(method.outputType().reference().name());
-      TypeNode repeatedResponseType = null;
-      for (Field field : methodOutputMessage.fields()) {
-        if (field.isRepeated() && !field.isMap()) {
-          Reference repeatedGenericRef = field.type().reference().generics().get(0);
-          repeatedResponseType = TypeNode.withReference(repeatedGenericRef);
-          break;
-        }
-      }
-
+      Field repeatedPagedResultsField = methodOutputMessage.findAndUnwrapFirstRepeatedField();
       Preconditions.checkNotNull(
-          repeatedResponseType,
+          repeatedPagedResultsField,
           String.format(
               "No repeated field found on message %s for method %s",
               methodOutputMessage.name(), method.name()));
 
+      TypeNode repeatedResponseType = repeatedPagedResultsField.type();
+
       nestedClasses.add(
           createNestedRpcPagedResponseClass(method, repeatedResponseType, messageTypes, types));
       nestedClasses.add(

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

@@ -478,20 +478,21 @@ private static MethodDefinition createRpcTestMethod(
           method, serviceName, classMemberVarExprs, resourceNames, messageTypes);
     }
     // Construct the expected response.
-    // TODO(miraleung): Paging here.
     TypeNode methodOutputType = method.hasLro() ? method.lro().responseType() : method.outputType();
     List<Expr> methodExprs = new ArrayList<>();
 
     TypeNode repeatedResponseType = null;
     VariableExpr responsesElementVarExpr = null;
     if (method.isPaged()) {
       Message methodOutputMessage = messageTypes.get(method.outputType().reference().name());
-      repeatedResponseType = findRepeatedPagedType(methodOutputMessage);
+      Field repeatedPagedResultsField = methodOutputMessage.findAndUnwrapFirstRepeatedField();
       Preconditions.checkNotNull(
-          repeatedResponseType,
+          repeatedPagedResultsField,
           String.format(
-              "No repeated type found for paged method %s with output message type %s",
+              "No repeated field found for paged method %s with output message type %s",
               method.name(), methodOutputMessage.name()));
+
+      repeatedResponseType = repeatedPagedResultsField.type();
       responsesElementVarExpr =
           VariableExpr.withVariable(
               Variable.builder().setType(repeatedResponseType).setName("responsesElement").build());
@@ -1832,16 +1833,6 @@ private static TypeNode getCallableType(Method protoMethod) {
         ConcreteReference.builder().setClazz(callableClazz).setGenerics(generics).build());
   }
 
-  private static TypeNode findRepeatedPagedType(Message message) {
-    for (Field field : message.fields()) {
-      if (field.isRepeated() && !field.isMap()) {
-        Reference repeatedGenericRef = field.type().reference().generics().get(0);
-        return TypeNode.withReference(repeatedGenericRef);
-      }
-    }
-    return null;
-  }
-
   private static String getCallableMethodName(Method protoMethod) {
     Preconditions.checkState(
         !protoMethod.stream().equals(Method.Stream.NONE),

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

@@ -354,28 +354,16 @@ private static List<Expr> createPagingStaticAssignExprs(
           String.format(
               "No method found for message type %s for method %s among %s",
               pagedResponseMessageKey, method.name(), messageTypes.keySet()));
-      TypeNode repeatedResponseType = null;
-      String repeatedFieldName = null;
-      for (Field field : pagedResponseMessage.fields()) {
-        Preconditions.checkState(
-            field != null,
-            String.format("Null field found for message %s", pagedResponseMessage.name()));
-        if (field.isRepeated() && !field.isMap()) {
-          // Field is currently a List-type.
-          Preconditions.checkState(
-              !field.type().reference().generics().isEmpty(),
-              String.format("No generics found for field reference %s", field.type().reference()));
-          repeatedResponseType = TypeNode.withReference(field.type().reference().generics().get(0));
-          repeatedFieldName = field.name();
-          break;
-        }
-      }
+      Field repeatedPagedResultsField = pagedResponseMessage.findAndUnwrapFirstRepeatedField();
       Preconditions.checkNotNull(
-          repeatedResponseType,
+          repeatedPagedResultsField,
           String.format(
               "No repeated type found for paged reesponse %s for method %s",
               method.outputType().reference().name(), method.name()));
 
+      TypeNode repeatedResponseType = repeatedPagedResultsField.type();
+      String repeatedFieldName = repeatedPagedResultsField.name();
+
       // Create the PAGE_STR_DESC variable.
       TypeNode pagedListDescType =
           TypeNode.withReference(

src/main/java/com/google/api/generator/gapic/model/Field.java

@@ -48,6 +48,8 @@ public boolean hasResourceReference() {
     return type().equals(TypeNode.STRING) && resourceReference() != null;
   }
 
+  abstract Builder toBuilder();
+
   public static Builder builder() {
     return new AutoValue_Field.Builder()
         .setIsMessage(false)

src/main/java/com/google/api/generator/gapic/model/Message.java

@@ -14,6 +14,7 @@
 
 package com.google.api.generator.gapic.model;
 
+import com.google.api.generator.engine.ast.Reference;
 import com.google.api.generator.engine.ast.TypeNode;
 import com.google.auto.value.AutoValue;
 import com.google.common.collect.ImmutableList;
@@ -46,6 +47,18 @@ public boolean hasResource() {
     return resource() != null;
   }
 
+  /** Returns the first list repeated field in a message, unwrapped from its list type. */
+  @Nullable
+  public Field findAndUnwrapFirstRepeatedField() {
+    for (Field field : fields()) {
+      if (field.isRepeated() && !field.isMap()) {
+        Reference repeatedGenericRef = field.type().reference().generics().get(0);
+        return field.toBuilder().setType(TypeNode.withReference(repeatedGenericRef)).build();
+      }
+    }
+    return null;
+  }
+
   public static Builder builder() {
     return new AutoValue_Message.Builder();
   }