public void setLastModifiedDate(Long lastModifiedDate) {
        this.lastModifiedDate = lastModifiedDate;
    }
<p>
The date and time when the collection was last modified.
</p>

@param lastModifiedDate
       The date and time when the collection was last modified.
aws-java-sdk-opensearchserverless/src/main/java/com/amazonaws/services/opensearchserverless/model/UpdateCollectionDetail.java