docs: public CreateSnapshotResponse createSnapshot(CreateSnapshotRequest request) {
          checkNotNull(request, "request should not be null.");
          if (Strings.isNullOrEmpty(request.getClientToken())) {
              request.setClientToken(this.generateClientToken());
          }
          checkStringNotEmpty(request.getVolumeId(), "request volumeId should not be empty.");
          checkStringNotEmpty(request.getSnapshotName(), "request snapshotName should not be empty.");
          InternalRequest internalRequest = this.createRequest(request, HttpMethodName.POST, SNAPSHOT_PREFIX);
          internalRequest.addParameter("clientToken", request.getClientToken());
          fillPayload(internalRequest, request);
          return invokeHttpClient(internalRequest, CreateSnapshotResponse.class);
      }