[FEATURE REQ] Azure Container Service (AKS) define with RBACenabled true is not possible?

I am using the azure-libraries-for-java to create a kubernetes cluster with withRBACEnabled true. The define() does not have the option withRBACEnabled and the cluster cannot be updated to set this property.
KubernetesCluster kubernetesCluster = azure.kubernetesClusters().define(kubernetesClusterVO.getAksName())
.withRegion(kubernetesClusterVO.getRegion())
.withNewResourceGroup(kubernetesClusterVO.getResourceGroupName())
.withLatestVersion()
.withRootUsername(kubernetesClusterVO.getRootUserName())
.withSshKey(sshKeys.getSshPublicKey())
.withServicePrincipalClientId(kubernetesClusterVO.getServicePrincipalClientId())
.withServicePrincipalSecret(kubernetesClusterVO.getServicePrincipalSecret())
.defineAgentPool(kubernetesClusterVO.getAgentpoolName())
.withVirtualMachineSize(kubernetesClusterVO.getVMSizeType())
.withAgentPoolVirtualMachineCount(kubernetesClusterVO.getAgentPoolVMCount())
.attach()
.withDnsPrefix(kubernetesClusterVO.getDnsNamePrefix())
.create();

The cluster is created with RBACEnabled false. No option to change it.

Update attempt using the java library
/**…more code..**/
item = item.update()
.withRBACEnabled()
.apply();

Error description
com.microsoft.azure.CloudException: Changing property 'enableRBAC' is not allowed.: Changing property 'enableRBAC' is not allowed.

Thank you.