Override admin::BigtableInstanceAdminClient Retry Policies

This shows how to override the retry policies for admin::BigtableInstanceAdminClient:

  auto options =
      google
::cloud::Options{}
         
.set<google::cloud::bigtable_admin::
                   
BigtableInstanceAdminConnectionIdempotencyPolicyOption>(
             
CustomIdempotencyPolicy().clone())
         
.set<google::cloud::bigtable_admin::
                   
BigtableInstanceAdminRetryPolicyOption>(
              google
::cloud::bigtable_admin::
                 
BigtableInstanceAdminLimitedErrorCountRetryPolicy(3)
                     
.clone())
         
.set<google::cloud::bigtable_admin::
                   
BigtableInstanceAdminBackoffPolicyOption>(
              google
::cloud::ExponentialBackoffPolicy(
                 
/*initial_delay=*/std::chrono::milliseconds(200),
                 
/*maximum_delay=*/std::chrono::seconds(45),
                 
/*scaling=*/2.0)
                 
.clone());
 
auto connection =
      google
::cloud::bigtable_admin::MakeBigtableInstanceAdminConnection(
          options
);

 
// c1 and c2 share the same retry policies
 
auto c1 =
      google
::cloud::bigtable_admin::BigtableInstanceAdminClient(connection);
 
auto c2 =
      google
::cloud::bigtable_admin::BigtableInstanceAdminClient(connection);

 
// You can override any of the policies in a new client. This new client
 
// will share the policies from c1 (or c2) *except* for the retry policy.
 
auto c3 = google::cloud::bigtable_admin::BigtableInstanceAdminClient(
      connection
, google::cloud::Options{}
                     
.set<google::cloud::bigtable_admin::
                               
BigtableInstanceAdminRetryPolicyOption>(
                          google
::cloud::bigtable_admin::
                             
BigtableInstanceAdminLimitedTimeRetryPolicy(
                                  std
::chrono::minutes(5))
                                 
.clone()));

 
// You can also override the policies in a single call:
 
// c3.SomeRpc(..., google::cloud::Options{}
 
//     .set<google::cloud::bigtable_admin::BigtableInstanceAdminRetryPolicyOption>(
 
//       google::cloud::bigtable_admin::BigtableInstanceAdminLimitedErrorCountRetryPolicy(10).clone()));

Assuming you have created a custom idempotency policy. Such as:

class CustomIdempotencyPolicy
   
: public google::cloud::bigtable_admin::
         
BigtableInstanceAdminConnectionIdempotencyPolicy {
 
public:
 
~CustomIdempotencyPolicy() override = default;
  std
::unique_ptr<google::cloud::bigtable_admin::
                     
BigtableInstanceAdminConnectionIdempotencyPolicy>
  clone
() const override {
   
return std::make_unique<CustomIdempotencyPolicy>(*this);
 
}
 
// Override inherited functions to define as needed.
};