public UpdateCostCategoryDefinitionRequest withRules(java.util.Collection<CostCategoryRule> rules) {
        setRules(rules);
        return this;
    }
<p>
The <code>Expression</code> object used to categorize costs. For more information, see <a
href="https://docs.aws.amazon.com/aws-cost-management/latest/APIReference/API_CostCategoryRule.html"
>CostCategoryRule </a>.
</p>

@param rules
       The <code>Expression</code> object used to categorize costs. For more information, see <a
       href="https://docs.aws.amazon.com/aws-cost-management/latest/APIReference/API_CostCategoryRule.html"
       >CostCategoryRule </a>.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-costexplorer/src/main/java/com/amazonaws/services/costexplorer/model/UpdateCostCategoryDefinitionRequest.java