Fix the default maxInboundMessageSize config via synth

Author: chingor13

google-api-grpc/proto-google-cloud-pubsub-v1/src/main/java/com/google/pubsub/v1/TopicNames.java

@@ -14,7 +14,6 @@
 
 package com.google.pubsub.v1;
 
-
 // AUTO-GENERATED DOCUMENTATION AND CLASS
 @javax.annotation.Generated("by GAPIC protoc plugin")
 public class TopicNames {

google-cloud-clients/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/v1/stub/SubscriberStubSettings.java

@@ -267,7 +267,7 @@ public static GoogleCredentialsProvider.Builder defaultCredentialsProviderBuilde
 
   /** Returns a builder for the default ChannelProvider for this service. */
   public static InstantiatingGrpcChannelProvider.Builder defaultGrpcTransportProviderBuilder() {
-    return InstantiatingGrpcChannelProvider.newBuilder();
+    return InstantiatingGrpcChannelProvider.newBuilder().setMaxInboundMessageSize(20 << 20); // 20MB
   }
 
   public static TransportChannelProvider defaultTransportChannelProvider() {

google-cloud-clients/google-cloud-pubsub/synth.py

@@ -35,6 +35,12 @@
   s.copy(library / f'grpc-google-cloud-{service}-{version}/src', f'../../google-api-grpc/grpc-google-cloud-{service}-{version}/src')
   s.copy(library / f'proto-google-cloud-{service}-{version}/src', f'../../google-api-grpc/proto-google-cloud-{service}-{version}/src')
 
+  s.replace(
+      '**/stub/SubscriberStubSettings.java',
+      r'return InstantiatingGrpcChannelProvider\.newBuilder\(\);',
+      'return InstantiatingGrpcChannelProvider.newBuilder().setMaxInboundMessageSize(20 << 20); // 20MB'
+  )
+
   java.format_code('./src')
   java.format_code(f'../../google-api-grpc/grpc-google-cloud-{service}-{version}/src')
   java.format_code(f'../../google-api-grpc/proto-google-cloud-{service}-{version}/src')