SDK returns StorageCapacity null

I'm using Java SDK to access VMWare VCoud Director.

I need same data from the VDC's (CPU used, CPU limit, memory used, etc.).

I've no problem with all data except "storage capacity" which is always null .

If I use a rest client, "Storage Capacity" brings a value, buy from SDK brings null.

My code to get "Storage Capacity is":

//capacityWithUsageType is always null

VdcType vdcType = currentVdc.getResource();

CapacityWithUsageType capacityWithUsageType = vdcType.getStorageCapacity();

//No problem to get CPU, for example...

ComputeCapacityType cct = vdcType.getComputeCapacity();

CapacityWithUsageType cpuType = cct.getCpu();

Thanks for any help or idea.