code: public Observable<RecordSetInner> updateAsync(String resourceGroupName, String zoneName, String relativeRecordSetName, RecordType recordType, RecordSetInner parameters, String ifMatch) {
          return updateWithServiceResponseAsync(resourceGroupName, zoneName, relativeRecordSetName, recordType, parameters, ifMatch).map(new Func1<ServiceResponse<RecordSetInner>, RecordSetInner>() {
              @Override
              public RecordSetInner call(ServiceResponse<RecordSetInner> response) {
                  return response.body();
              }
          });
      }
docs: Updates a record set within a DNS zone.
  
  @param resourceGroupName The name of the resource group.
  @param zoneName The name of the DNS zone (without a terminating dot).
  @param relativeRecordSetName The name of the record set, relative to the name of the zone.
  @param recordType The type of DNS record in this record set. Possible values include: 'A', 'AAAA', 'CNAME', 'MX', 'NS', 'PTR', 'SOA', 'SRV', 'TXT'
  @param parameters Parameters supplied to the Update operation.
  @param ifMatch The etag of the record set. Omit this value to always overwrite the current record set. Specify the last-seen etag value to prevent accidentally overwritting concurrent changes.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the RecordSetInner object