public void setKey(String key) {
        this.key = key;
    }
<p>
The key in a key-value pair that describes the margin summary.
</p>

@param key
       The key in a key-value pair that describes the margin summary.
aws-java-sdk-billingconductor/src/main/java/com/amazonaws/services/billingconductor/model/Attribute.java