Make fields optional. Also change max_cache_age to be a Duration

build.sbt

@@ -71,6 +71,7 @@ lazy val root = (project in file("."))
     libraryDependencies ++= Seq(
       // Required for gRPC Protobuf
       "javax.annotation" % "javax.annotation-api" % "1.3.2",
+      "com.google.protobuf" % "protobuf-java" % "3.25.4" % "protobuf", // so it's on the ProtobufConfig classpath
       "io.grpc" % "grpc-netty" % (ProtobufConfig / protobufGrpcVersion).value,
       "io.grpc" % "grpc-protobuf" % (ProtobufConfig / protobufGrpcVersion).value,
       "io.grpc" % "grpc-stub" % (ProtobufConfig / protobufGrpcVersion).value

src/main/protobuf/com/rawlabs/protocol/das/v1/services/tables_service.proto

@@ -17,6 +17,8 @@ option java_multiple_files = true;
 
 package com.rawlabs.protocol.das.v1.services;
 
+import "google/protobuf/duration.proto";
+
 import "com/rawlabs/protocol/das/v1/common/das.proto";
 import "com/rawlabs/protocol/das/v1/common/environment.proto";
 import "com/rawlabs/protocol/das/v1/tables/tables.proto";
@@ -111,9 +113,10 @@ message ExecuteTableRequest {
     com.rawlabs.protocol.das.v1.query.Query query = 3;
     optional string plan_id = 4;
     // Maximum size in bytes for each batch of query results.
-    uint32 max_batch_size_bytes = 5;
+    optional uint32 max_batch_size_bytes = 5;
     // Maximum allowable age of an existing cache to consider for reuse.
-    uint32 max_cache_age_seconds = 6;
+    // When missing, caches are ignored.
+    optional google.protobuf.Duration max_cache_age = 6;
     optional com.rawlabs.protocol.das.v1.common.Environment env = 99;
 }