Setting the Build Label in Operation Participant (server)

Hi team,

I'm trying to set the label of a build in an operation participant but I can't it.
I don't understand how to make the change from "IItemsResponse" to "IBuildResult"

In a snippet, it is easy:

https://jazz.net/wiki/bin/view/Main/BuildJavaProgrammingExamples

ITeamBuildClient buildClient = (ITeamBuildClient) teamRepository.getClientLibrary(ITeamBuildClient.class);
IBuildDefinition buildDefinition = buildClient.getBuildDefinition(buildDefinitionId, monitor);

ITeamBuildRequestClient requestClient = (ITeamBuildRequestClient) teamRepository.getClientLibrary(ITeamBuildRequestClient.class);
IBuildRequest buildRequest = requestClient.requestBuild(buildDefinition, true, monitor);

String[] properties = new String[] { IBuildResult.PROPERTY_LABEL };

IBuildResult buildResult = (IBuildResult) teamRepository.itemManager().fetchPartialItem(
buildRequest.getBuildResult(), IItemManager.REFRESH, Arrays.asList(properties), monitor);

String label = "Set Build Label Snippet build";
buildResult = (IBuildResult) buildResult.getWorkingCopy();
buildResult.setLabel(label);

buildClient.save(buildResult, monitor);


But in an operation participant:

......

IItemsResponse itemsresponse = buildRequestService.requestBuild((IBuildDefinitionHandle)buildService.getBuildDefinition(buildDefinition).getItemHandle(), buildProperties, null, true, false);

IItemsResponse --> IBuildResult ?????

Could you help me?
Any help would be appreciated

Thanks in advance!!!

Best regards,
Javier Lisbona