code: public Observable<UsagesResultInner> getUsagesAsync(String resourceGroupName, String accountName, String filter) {
          return getUsagesWithServiceResponseAsync(resourceGroupName, accountName, filter).map(new Func1<ServiceResponse<UsagesResultInner>, UsagesResultInner>() {
              @Override
              public UsagesResultInner call(ServiceResponse<UsagesResultInner> response) {
                  return response.body();
              }
          });
      }
docs: Get usages for the requested Cognitive Services account.
  
  @param resourceGroupName The name of the resource group within the user's subscription.
  @param accountName The name of Cognitive Services account.
  @param filter An OData filter expression that describes a subset of usages to return. The supported parameter is name.value (name of the metric, can have an or of multiple names).
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the UsagesResultInner object