public void setKey(String key) {
        this.key = key;
    }
<p>
The identifier of the target document attribute or metadata field. For example, 'Department' could be an
identifier for the target attribute or metadata field that includes the department names associated with the
documents.
</p>

@param key
       The identifier of the target document attribute or metadata field. For example, 'Department' could be an
       identifier for the target attribute or metadata field that includes the department names associated with
       the documents.
aws-java-sdk-qbusiness/src/main/java/com/amazonaws/services/qbusiness/model/DocumentAttributeTarget.java