Program: 48302
Project: 48302
Buggy source:
public ApiRequest startComponents(String clusterName,List<String> hostNames,List<String> components) throws AmbariApiException {
  ApiHostsRequest hostsRequest=new ApiHostsRequest();
  ApiHostComponentsRequest apiComponents=new ApiHostComponentsRequest();
  hostsRequest.setBody(apiComponents);
  ApiComponentInfo hostRoles=new ApiComponentInfo();
  hostRoles.setState("String_Node_Str");
  apiComponents.setHostRoles(hostRoles);
  ApiHostsRequestInfo requestInfo=new ApiHostsRequestInfo();
  hostsRequest.setRequestInfo(requestInfo);
  requestInfo.setContext("String_Node_Str");
  StringBuilder builder=new StringBuilder();
  builder.append("String_Node_Str");
  for (  String hostName : hostNames) {
    builder.append(hostName).append("String_Node_Str");
  }
  builder.deleteCharAt(builder.length() - 1);
  builder.append("String_Node_Str").append("String_Node_Str");
  builder.append("String_Node_Str");
  for (  String component : components) {
    builder.append(component).append("String_Node_Str");
  }
  builder.deleteCharAt(builder.length() - 1);
  builder.append("String_Node_Str");
  requestInfo.setQueryString(builder.toString());
  String startJson=ApiUtils.objectToJson(hostsRequest);
  logger.debug("String_Node_Str" + startJson);
  Response response=null;
  try {
    response=apiResourceRootV1.getClustersResource().getHostComponentsResource(clusterName).operationWithFilter(startJson);
  }
 catch (  Exception e) {
    throw AmbariApiException.CANNOT_CONNECT_AMBARI_SERVER(e);
  }
  String responseJson=handleAmbariResponse(response);
  logger.debug("String_Node_Str" + responseJson);
  return ApiUtils.jsonToObject(ApiRequest.class,responseJson);
}

Fixed version (ground truth):
@Override public ApiRequest startComponents(String clusterName,List<String> hostNames,List<String> components) throws AmbariApiException {
  ApiHostsRequest hostsRequest=new ApiHostsRequest();
  ApiHostComponentsRequest apiComponents=new ApiHostComponentsRequest();
  hostsRequest.setBody(apiComponents);
  ApiComponentInfo hostRoles=new ApiComponentInfo();
  hostRoles.setState("String_Node_Str");
  apiComponents.setHostRoles(hostRoles);
  ApiHostsRequestInfo requestInfo=new ApiHostsRequestInfo();
  hostsRequest.setRequestInfo(requestInfo);
  requestInfo.setContext("String_Node_Str");
  StringBuilder builder=new StringBuilder();
  builder.append("String_Node_Str");
  for (  String hostName : hostNames) {
    builder.append(hostName).append("String_Node_Str");
  }
  builder.deleteCharAt(builder.length() - 1);
  builder.append("String_Node_Str").append("String_Node_Str");
  builder.append("String_Node_Str");
  for (  String component : components) {
    builder.append(component).append("String_Node_Str");
  }
  builder.deleteCharAt(builder.length() - 1);
  builder.append("String_Node_Str");
  requestInfo.setQueryString(builder.toString());
  String startJson=ApiUtils.objectToJson(hostsRequest);
  logger.debug("String_Node_Str" + startJson);
  Response response=null;
  try {
    response=apiResourceRootV1.getClustersResource().getHostComponentsResource(clusterName).operationWithFilter(startJson);
  }
 catch (  Exception e) {
    throw AmbariApiException.CANNOT_CONNECT_AMBARI_SERVER(e);
  }
  String responseJson=handleAmbariResponse(response);
  logger.debug("String_Node_Str" + responseJson);
  return ApiUtils.jsonToObject(ApiRequest.class,responseJson);
}