public String getDirectoryId() {
        return this.directoryId;
    }
<p>
The identifier of the directory. If any WorkSpaces are registered to this directory, you must remove them before
you deregister the directory, or you will receive an OperationNotSupportedException error.
</p>

@return The identifier of the directory. If any WorkSpaces are registered to this directory, you must remove them
        before you deregister the directory, or you will receive an OperationNotSupportedException error.
aws-java-sdk-workspaces/src/main/java/com/amazonaws/services/workspaces/model/DeregisterWorkspaceDirectoryRequest.java