diff --git a/src/v1/database_admin_client.ts b/src/v1/database_admin_client.ts
index 0f63ac46a..25ebfa220 100644
--- a/src/v1/database_admin_client.ts
+++ b/src/v1/database_admin_client.ts
@@ -412,7 +412,7 @@ export class DatabaseAdminClient {
   // -- Service calls --
   // -------------------
   getDatabase(
-    request: protos.google.spanner.admin.database.v1.IGetDatabaseRequest,
+    request?: protos.google.spanner.admin.database.v1.IGetDatabaseRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -461,7 +461,7 @@ export class DatabaseAdminClient {
    * const [response] = await client.getDatabase(request);
    */
   getDatabase(
-    request: protos.google.spanner.admin.database.v1.IGetDatabaseRequest,
+    request?: protos.google.spanner.admin.database.v1.IGetDatabaseRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -504,7 +504,7 @@ export class DatabaseAdminClient {
     return this.innerApiCalls.getDatabase(request, options, callback);
   }
   dropDatabase(
-    request: protos.google.spanner.admin.database.v1.IDropDatabaseRequest,
+    request?: protos.google.spanner.admin.database.v1.IDropDatabaseRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -554,7 +554,7 @@ export class DatabaseAdminClient {
    * const [response] = await client.dropDatabase(request);
    */
   dropDatabase(
-    request: protos.google.spanner.admin.database.v1.IDropDatabaseRequest,
+    request?: protos.google.spanner.admin.database.v1.IDropDatabaseRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -597,7 +597,7 @@ export class DatabaseAdminClient {
     return this.innerApiCalls.dropDatabase(request, options, callback);
   }
   getDatabaseDdl(
-    request: protos.google.spanner.admin.database.v1.IGetDatabaseDdlRequest,
+    request?: protos.google.spanner.admin.database.v1.IGetDatabaseDdlRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -652,7 +652,7 @@ export class DatabaseAdminClient {
    * const [response] = await client.getDatabaseDdl(request);
    */
   getDatabaseDdl(
-    request: protos.google.spanner.admin.database.v1.IGetDatabaseDdlRequest,
+    request?: protos.google.spanner.admin.database.v1.IGetDatabaseDdlRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -698,7 +698,7 @@ export class DatabaseAdminClient {
     return this.innerApiCalls.getDatabaseDdl(request, options, callback);
   }
   setIamPolicy(
-    request: protos.google.iam.v1.ISetIamPolicyRequest,
+    request?: protos.google.iam.v1.ISetIamPolicyRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -754,7 +754,7 @@ export class DatabaseAdminClient {
    * const [response] = await client.setIamPolicy(request);
    */
   setIamPolicy(
-    request: protos.google.iam.v1.ISetIamPolicyRequest,
+    request?: protos.google.iam.v1.ISetIamPolicyRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -793,7 +793,7 @@ export class DatabaseAdminClient {
     return this.innerApiCalls.setIamPolicy(request, options, callback);
   }
   getIamPolicy(
-    request: protos.google.iam.v1.IGetIamPolicyRequest,
+    request?: protos.google.iam.v1.IGetIamPolicyRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -848,7 +848,7 @@ export class DatabaseAdminClient {
    * const [response] = await client.getIamPolicy(request);
    */
   getIamPolicy(
-    request: protos.google.iam.v1.IGetIamPolicyRequest,
+    request?: protos.google.iam.v1.IGetIamPolicyRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -887,7 +887,7 @@ export class DatabaseAdminClient {
     return this.innerApiCalls.getIamPolicy(request, options, callback);
   }
   testIamPermissions(
-    request: protos.google.iam.v1.ITestIamPermissionsRequest,
+    request?: protos.google.iam.v1.ITestIamPermissionsRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -946,7 +946,7 @@ export class DatabaseAdminClient {
    * const [response] = await client.testIamPermissions(request);
    */
   testIamPermissions(
-    request: protos.google.iam.v1.ITestIamPermissionsRequest,
+    request?: protos.google.iam.v1.ITestIamPermissionsRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -985,7 +985,7 @@ export class DatabaseAdminClient {
     return this.innerApiCalls.testIamPermissions(request, options, callback);
   }
   getBackup(
-    request: protos.google.spanner.admin.database.v1.IGetBackupRequest,
+    request?: protos.google.spanner.admin.database.v1.IGetBackupRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1035,7 +1035,7 @@ export class DatabaseAdminClient {
    * const [response] = await client.getBackup(request);
    */
   getBackup(
-    request: protos.google.spanner.admin.database.v1.IGetBackupRequest,
+    request?: protos.google.spanner.admin.database.v1.IGetBackupRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1078,7 +1078,7 @@ export class DatabaseAdminClient {
     return this.innerApiCalls.getBackup(request, options, callback);
   }
   updateBackup(
-    request: protos.google.spanner.admin.database.v1.IUpdateBackupRequest,
+    request?: protos.google.spanner.admin.database.v1.IUpdateBackupRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1135,7 +1135,7 @@ export class DatabaseAdminClient {
    * const [response] = await client.updateBackup(request);
    */
   updateBackup(
-    request: protos.google.spanner.admin.database.v1.IUpdateBackupRequest,
+    request?: protos.google.spanner.admin.database.v1.IUpdateBackupRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1178,7 +1178,7 @@ export class DatabaseAdminClient {
     return this.innerApiCalls.updateBackup(request, options, callback);
   }
   deleteBackup(
-    request: protos.google.spanner.admin.database.v1.IDeleteBackupRequest,
+    request?: protos.google.spanner.admin.database.v1.IDeleteBackupRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1228,7 +1228,7 @@ export class DatabaseAdminClient {
    * const [response] = await client.deleteBackup(request);
    */
   deleteBackup(
-    request: protos.google.spanner.admin.database.v1.IDeleteBackupRequest,
+    request?: protos.google.spanner.admin.database.v1.IDeleteBackupRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1272,7 +1272,7 @@ export class DatabaseAdminClient {
   }
 
   createDatabase(
-    request: protos.google.spanner.admin.database.v1.ICreateDatabaseRequest,
+    request?: protos.google.spanner.admin.database.v1.ICreateDatabaseRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1351,7 +1351,7 @@ export class DatabaseAdminClient {
    * const [response] = await operation.promise();
    */
   createDatabase(
-    request: protos.google.spanner.admin.database.v1.ICreateDatabaseRequest,
+    request?: protos.google.spanner.admin.database.v1.ICreateDatabaseRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1436,7 +1436,7 @@ export class DatabaseAdminClient {
     >;
   }
   updateDatabaseDdl(
-    request: protos.google.spanner.admin.database.v1.IUpdateDatabaseDdlRequest,
+    request?: protos.google.spanner.admin.database.v1.IUpdateDatabaseDdlRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1520,7 +1520,7 @@ export class DatabaseAdminClient {
    * const [response] = await operation.promise();
    */
   updateDatabaseDdl(
-    request: protos.google.spanner.admin.database.v1.IUpdateDatabaseDdlRequest,
+    request?: protos.google.spanner.admin.database.v1.IUpdateDatabaseDdlRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1605,7 +1605,7 @@ export class DatabaseAdminClient {
     >;
   }
   createBackup(
-    request: protos.google.spanner.admin.database.v1.ICreateBackupRequest,
+    request?: protos.google.spanner.admin.database.v1.ICreateBackupRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1689,7 +1689,7 @@ export class DatabaseAdminClient {
    * const [response] = await operation.promise();
    */
   createBackup(
-    request: protos.google.spanner.admin.database.v1.ICreateBackupRequest,
+    request?: protos.google.spanner.admin.database.v1.ICreateBackupRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1774,7 +1774,7 @@ export class DatabaseAdminClient {
     >;
   }
   restoreDatabase(
-    request: protos.google.spanner.admin.database.v1.IRestoreDatabaseRequest,
+    request?: protos.google.spanner.admin.database.v1.IRestoreDatabaseRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1865,7 +1865,7 @@ export class DatabaseAdminClient {
    * const [response] = await operation.promise();
    */
   restoreDatabase(
-    request: protos.google.spanner.admin.database.v1.IRestoreDatabaseRequest,
+    request?: protos.google.spanner.admin.database.v1.IRestoreDatabaseRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1950,7 +1950,7 @@ export class DatabaseAdminClient {
     >;
   }
   listDatabases(
-    request: protos.google.spanner.admin.database.v1.IListDatabasesRequest,
+    request?: protos.google.spanner.admin.database.v1.IListDatabasesRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -2009,7 +2009,7 @@ export class DatabaseAdminClient {
    *   for more details and examples.
    */
   listDatabases(
-    request: protos.google.spanner.admin.database.v1.IListDatabasesRequest,
+    request?: protos.google.spanner.admin.database.v1.IListDatabasesRequest,
     optionsOrCallback?:
       | CallOptions
       | PaginationCallback<
@@ -2153,7 +2153,7 @@ export class DatabaseAdminClient {
     ) as AsyncIterable<protos.google.spanner.admin.database.v1.IDatabase>;
   }
   listBackups(
-    request: protos.google.spanner.admin.database.v1.IListBackupsRequest,
+    request?: protos.google.spanner.admin.database.v1.IListBackupsRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -2251,7 +2251,7 @@ export class DatabaseAdminClient {
    *   for more details and examples.
    */
   listBackups(
-    request: protos.google.spanner.admin.database.v1.IListBackupsRequest,
+    request?: protos.google.spanner.admin.database.v1.IListBackupsRequest,
     optionsOrCallback?:
       | CallOptions
       | PaginationCallback<
@@ -2469,7 +2469,7 @@ export class DatabaseAdminClient {
     ) as AsyncIterable<protos.google.spanner.admin.database.v1.IBackup>;
   }
   listDatabaseOperations(
-    request: protos.google.spanner.admin.database.v1.IListDatabaseOperationsRequest,
+    request?: protos.google.spanner.admin.database.v1.IListDatabaseOperationsRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -2577,7 +2577,7 @@ export class DatabaseAdminClient {
    *   for more details and examples.
    */
   listDatabaseOperations(
-    request: protos.google.spanner.admin.database.v1.IListDatabaseOperationsRequest,
+    request?: protos.google.spanner.admin.database.v1.IListDatabaseOperationsRequest,
     optionsOrCallback?:
       | CallOptions
       | PaginationCallback<
@@ -2809,7 +2809,7 @@ export class DatabaseAdminClient {
     ) as AsyncIterable<protos.google.longrunning.IOperation>;
   }
   listBackupOperations(
-    request: protos.google.spanner.admin.database.v1.IListBackupOperationsRequest,
+    request?: protos.google.spanner.admin.database.v1.IListBackupOperationsRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -2917,7 +2917,7 @@ export class DatabaseAdminClient {
    *   for more details and examples.
    */
   listBackupOperations(
-    request: protos.google.spanner.admin.database.v1.IListBackupOperationsRequest,
+    request?: protos.google.spanner.admin.database.v1.IListBackupOperationsRequest,
     optionsOrCallback?:
       | CallOptions
       | PaginationCallback<
diff --git a/src/v1/instance_admin_client.ts b/src/v1/instance_admin_client.ts
index d1553afaa..c4a721022 100644
--- a/src/v1/instance_admin_client.ts
+++ b/src/v1/instance_admin_client.ts
@@ -385,7 +385,7 @@ export class InstanceAdminClient {
   // -- Service calls --
   // -------------------
   getInstanceConfig(
-    request: protos.google.spanner.admin.instance.v1.IGetInstanceConfigRequest,
+    request?: protos.google.spanner.admin.instance.v1.IGetInstanceConfigRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -437,7 +437,7 @@ export class InstanceAdminClient {
    * const [response] = await client.getInstanceConfig(request);
    */
   getInstanceConfig(
-    request: protos.google.spanner.admin.instance.v1.IGetInstanceConfigRequest,
+    request?: protos.google.spanner.admin.instance.v1.IGetInstanceConfigRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -483,7 +483,7 @@ export class InstanceAdminClient {
     return this.innerApiCalls.getInstanceConfig(request, options, callback);
   }
   getInstance(
-    request: protos.google.spanner.admin.instance.v1.IGetInstanceRequest,
+    request?: protos.google.spanner.admin.instance.v1.IGetInstanceRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -536,7 +536,7 @@ export class InstanceAdminClient {
    * const [response] = await client.getInstance(request);
    */
   getInstance(
-    request: protos.google.spanner.admin.instance.v1.IGetInstanceRequest,
+    request?: protos.google.spanner.admin.instance.v1.IGetInstanceRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -579,7 +579,7 @@ export class InstanceAdminClient {
     return this.innerApiCalls.getInstance(request, options, callback);
   }
   deleteInstance(
-    request: protos.google.spanner.admin.instance.v1.IDeleteInstanceRequest,
+    request?: protos.google.spanner.admin.instance.v1.IDeleteInstanceRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -641,7 +641,7 @@ export class InstanceAdminClient {
    * const [response] = await client.deleteInstance(request);
    */
   deleteInstance(
-    request: protos.google.spanner.admin.instance.v1.IDeleteInstanceRequest,
+    request?: protos.google.spanner.admin.instance.v1.IDeleteInstanceRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -687,7 +687,7 @@ export class InstanceAdminClient {
     return this.innerApiCalls.deleteInstance(request, options, callback);
   }
   setIamPolicy(
-    request: protos.google.iam.v1.ISetIamPolicyRequest,
+    request?: protos.google.iam.v1.ISetIamPolicyRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -741,7 +741,7 @@ export class InstanceAdminClient {
    * const [response] = await client.setIamPolicy(request);
    */
   setIamPolicy(
-    request: protos.google.iam.v1.ISetIamPolicyRequest,
+    request?: protos.google.iam.v1.ISetIamPolicyRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -780,7 +780,7 @@ export class InstanceAdminClient {
     return this.innerApiCalls.setIamPolicy(request, options, callback);
   }
   getIamPolicy(
-    request: protos.google.iam.v1.IGetIamPolicyRequest,
+    request?: protos.google.iam.v1.IGetIamPolicyRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -832,7 +832,7 @@ export class InstanceAdminClient {
    * const [response] = await client.getIamPolicy(request);
    */
   getIamPolicy(
-    request: protos.google.iam.v1.IGetIamPolicyRequest,
+    request?: protos.google.iam.v1.IGetIamPolicyRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -871,7 +871,7 @@ export class InstanceAdminClient {
     return this.innerApiCalls.getIamPolicy(request, options, callback);
   }
   testIamPermissions(
-    request: protos.google.iam.v1.ITestIamPermissionsRequest,
+    request?: protos.google.iam.v1.ITestIamPermissionsRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -926,7 +926,7 @@ export class InstanceAdminClient {
    * const [response] = await client.testIamPermissions(request);
    */
   testIamPermissions(
-    request: protos.google.iam.v1.ITestIamPermissionsRequest,
+    request?: protos.google.iam.v1.ITestIamPermissionsRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -966,7 +966,7 @@ export class InstanceAdminClient {
   }
 
   createInstance(
-    request: protos.google.spanner.admin.instance.v1.ICreateInstanceRequest,
+    request?: protos.google.spanner.admin.instance.v1.ICreateInstanceRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1063,7 +1063,7 @@ export class InstanceAdminClient {
    * const [response] = await operation.promise();
    */
   createInstance(
-    request: protos.google.spanner.admin.instance.v1.ICreateInstanceRequest,
+    request?: protos.google.spanner.admin.instance.v1.ICreateInstanceRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1148,7 +1148,7 @@ export class InstanceAdminClient {
     >;
   }
   updateInstance(
-    request: protos.google.spanner.admin.instance.v1.IUpdateInstanceRequest,
+    request?: protos.google.spanner.admin.instance.v1.IUpdateInstanceRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1249,7 +1249,7 @@ export class InstanceAdminClient {
    * const [response] = await operation.promise();
    */
   updateInstance(
-    request: protos.google.spanner.admin.instance.v1.IUpdateInstanceRequest,
+    request?: protos.google.spanner.admin.instance.v1.IUpdateInstanceRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1334,7 +1334,7 @@ export class InstanceAdminClient {
     >;
   }
   listInstanceConfigs(
-    request: protos.google.spanner.admin.instance.v1.IListInstanceConfigsRequest,
+    request?: protos.google.spanner.admin.instance.v1.IListInstanceConfigsRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1394,7 +1394,7 @@ export class InstanceAdminClient {
    *   for more details and examples.
    */
   listInstanceConfigs(
-    request: protos.google.spanner.admin.instance.v1.IListInstanceConfigsRequest,
+    request?: protos.google.spanner.admin.instance.v1.IListInstanceConfigsRequest,
     optionsOrCallback?:
       | CallOptions
       | PaginationCallback<
@@ -1540,7 +1540,7 @@ export class InstanceAdminClient {
     ) as AsyncIterable<protos.google.spanner.admin.instance.v1.IInstanceConfig>;
   }
   listInstances(
-    request: protos.google.spanner.admin.instance.v1.IListInstancesRequest,
+    request?: protos.google.spanner.admin.instance.v1.IListInstancesRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1619,7 +1619,7 @@ export class InstanceAdminClient {
    *   for more details and examples.
    */
   listInstances(
-    request: protos.google.spanner.admin.instance.v1.IListInstancesRequest,
+    request?: protos.google.spanner.admin.instance.v1.IListInstancesRequest,
     optionsOrCallback?:
       | CallOptions
       | PaginationCallback<
diff --git a/src/v1/spanner_client.ts b/src/v1/spanner_client.ts
index ca7c7fc32..db1fdba3e 100644
--- a/src/v1/spanner_client.ts
+++ b/src/v1/spanner_client.ts
@@ -336,7 +336,7 @@ export class SpannerClient {
   // -- Service calls --
   // -------------------
   createSession(
-    request: protos.google.spanner.v1.ICreateSessionRequest,
+    request?: protos.google.spanner.v1.ICreateSessionRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -400,7 +400,7 @@ export class SpannerClient {
    * const [response] = await client.createSession(request);
    */
   createSession(
-    request: protos.google.spanner.v1.ICreateSessionRequest,
+    request?: protos.google.spanner.v1.ICreateSessionRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -439,7 +439,7 @@ export class SpannerClient {
     return this.innerApiCalls.createSession(request, options, callback);
   }
   batchCreateSessions(
-    request: protos.google.spanner.v1.IBatchCreateSessionsRequest,
+    request?: protos.google.spanner.v1.IBatchCreateSessionsRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -494,7 +494,7 @@ export class SpannerClient {
    * const [response] = await client.batchCreateSessions(request);
    */
   batchCreateSessions(
-    request: protos.google.spanner.v1.IBatchCreateSessionsRequest,
+    request?: protos.google.spanner.v1.IBatchCreateSessionsRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -535,7 +535,7 @@ export class SpannerClient {
     return this.innerApiCalls.batchCreateSessions(request, options, callback);
   }
   getSession(
-    request: protos.google.spanner.v1.IGetSessionRequest,
+    request?: protos.google.spanner.v1.IGetSessionRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -581,7 +581,7 @@ export class SpannerClient {
    * const [response] = await client.getSession(request);
    */
   getSession(
-    request: protos.google.spanner.v1.IGetSessionRequest,
+    request?: protos.google.spanner.v1.IGetSessionRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -620,7 +620,7 @@ export class SpannerClient {
     return this.innerApiCalls.getSession(request, options, callback);
   }
   deleteSession(
-    request: protos.google.spanner.v1.IDeleteSessionRequest,
+    request?: protos.google.spanner.v1.IDeleteSessionRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -666,7 +666,7 @@ export class SpannerClient {
    * const [response] = await client.deleteSession(request);
    */
   deleteSession(
-    request: protos.google.spanner.v1.IDeleteSessionRequest,
+    request?: protos.google.spanner.v1.IDeleteSessionRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -705,7 +705,7 @@ export class SpannerClient {
     return this.innerApiCalls.deleteSession(request, options, callback);
   }
   executeSql(
-    request: protos.google.spanner.v1.IExecuteSqlRequest,
+    request?: protos.google.spanner.v1.IExecuteSqlRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -826,7 +826,7 @@ export class SpannerClient {
    * const [response] = await client.executeSql(request);
    */
   executeSql(
-    request: protos.google.spanner.v1.IExecuteSqlRequest,
+    request?: protos.google.spanner.v1.IExecuteSqlRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -865,7 +865,7 @@ export class SpannerClient {
     return this.innerApiCalls.executeSql(request, options, callback);
   }
   executeBatchDml(
-    request: protos.google.spanner.v1.IExecuteBatchDmlRequest,
+    request?: protos.google.spanner.v1.IExecuteBatchDmlRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -943,7 +943,7 @@ export class SpannerClient {
    * const [response] = await client.executeBatchDml(request);
    */
   executeBatchDml(
-    request: protos.google.spanner.v1.IExecuteBatchDmlRequest,
+    request?: protos.google.spanner.v1.IExecuteBatchDmlRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -982,7 +982,7 @@ export class SpannerClient {
     return this.innerApiCalls.executeBatchDml(request, options, callback);
   }
   read(
-    request: protos.google.spanner.v1.IReadRequest,
+    request?: protos.google.spanner.v1.IReadRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1081,7 +1081,7 @@ export class SpannerClient {
    * const [response] = await client.read(request);
    */
   read(
-    request: protos.google.spanner.v1.IReadRequest,
+    request?: protos.google.spanner.v1.IReadRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1120,7 +1120,7 @@ export class SpannerClient {
     return this.innerApiCalls.read(request, options, callback);
   }
   beginTransaction(
-    request: protos.google.spanner.v1.IBeginTransactionRequest,
+    request?: protos.google.spanner.v1.IBeginTransactionRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1175,7 +1175,7 @@ export class SpannerClient {
    * const [response] = await client.beginTransaction(request);
    */
   beginTransaction(
-    request: protos.google.spanner.v1.IBeginTransactionRequest,
+    request?: protos.google.spanner.v1.IBeginTransactionRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1214,7 +1214,7 @@ export class SpannerClient {
     return this.innerApiCalls.beginTransaction(request, options, callback);
   }
   commit(
-    request: protos.google.spanner.v1.ICommitRequest,
+    request?: protos.google.spanner.v1.ICommitRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1293,7 +1293,7 @@ export class SpannerClient {
    * const [response] = await client.commit(request);
    */
   commit(
-    request: protos.google.spanner.v1.ICommitRequest,
+    request?: protos.google.spanner.v1.ICommitRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1332,7 +1332,7 @@ export class SpannerClient {
     return this.innerApiCalls.commit(request, options, callback);
   }
   rollback(
-    request: protos.google.spanner.v1.IRollbackRequest,
+    request?: protos.google.spanner.v1.IRollbackRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1385,7 +1385,7 @@ export class SpannerClient {
    * const [response] = await client.rollback(request);
    */
   rollback(
-    request: protos.google.spanner.v1.IRollbackRequest,
+    request?: protos.google.spanner.v1.IRollbackRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1424,7 +1424,7 @@ export class SpannerClient {
     return this.innerApiCalls.rollback(request, options, callback);
   }
   partitionQuery(
-    request: protos.google.spanner.v1.IPartitionQueryRequest,
+    request?: protos.google.spanner.v1.IPartitionQueryRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1516,7 +1516,7 @@ export class SpannerClient {
    * const [response] = await client.partitionQuery(request);
    */
   partitionQuery(
-    request: protos.google.spanner.v1.IPartitionQueryRequest,
+    request?: protos.google.spanner.v1.IPartitionQueryRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1555,7 +1555,7 @@ export class SpannerClient {
     return this.innerApiCalls.partitionQuery(request, options, callback);
   }
   partitionRead(
-    request: protos.google.spanner.v1.IPartitionReadRequest,
+    request?: protos.google.spanner.v1.IPartitionReadRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1633,7 +1633,7 @@ export class SpannerClient {
    * const [response] = await client.partitionRead(request);
    */
   partitionRead(
-    request: protos.google.spanner.v1.IPartitionReadRequest,
+    request?: protos.google.spanner.v1.IPartitionReadRequest,
     optionsOrCallback?:
       | CallOptions
       | Callback<
@@ -1861,7 +1861,7 @@ export class SpannerClient {
   }
 
   listSessions(
-    request: protos.google.spanner.v1.IListSessionsRequest,
+    request?: protos.google.spanner.v1.IListSessionsRequest,
     options?: CallOptions
   ): Promise<
     [
@@ -1926,7 +1926,7 @@ export class SpannerClient {
    *   for more details and examples.
    */
   listSessions(
-    request: protos.google.spanner.v1.IListSessionsRequest,
+    request?: protos.google.spanner.v1.IListSessionsRequest,
     optionsOrCallback?:
       | CallOptions
       | PaginationCallback<