public DeleteStackInstancesRequest withOperationId(String operationId) {
        setOperationId(operationId);
        return this;
    }
<p>
The unique identifier for this stack set operation.
</p>
<p>
If you don't specify an operation ID, the SDK generates one automatically.
</p>
<p>
The operation ID also functions as an idempotency token, to ensure that CloudFormation performs the stack set
operation only once, even if you retry the request multiple times. You can retry stack set operation requests to
ensure that CloudFormation successfully received them.
</p>
<p>
Repeating this stack set operation with a new operation ID retries all stack instances whose status is
<code>OUTDATED</code>.
</p>

@param operationId
       The unique identifier for this stack set operation.</p>
       <p>
       If you don't specify an operation ID, the SDK generates one automatically.
       </p>
       <p>
       The operation ID also functions as an idempotency token, to ensure that CloudFormation performs the stack
       set operation only once, even if you retry the request multiple times. You can retry stack set operation
       requests to ensure that CloudFormation successfully received them.
       </p>
       <p>
       Repeating this stack set operation with a new operation ID retries all stack instances whose status is
       <code>OUTDATED</code>.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-cloudformation/src/main/java/com/amazonaws/services/cloudformation/model/DeleteStackInstancesRequest.java