List in Groovy and how to pass as parameter

I am trying to create a workflow to bulk approve Workflow Tasks. When I pass List to CompleteWorkflowTasksRequest.setTaskIds method, it errors out.

CompleteWorkflowTasksRequest.setIds requires List<UUID> as parameter. 

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import com.collibra.dgc.core.api.dto.workflow.FindWorkflowTasksRequest
import com.collibra.dgc.core.api.dto.PagedResponse
import com.collibra.dgc.core.api.dto.workflow.CompleteWorkflowTasksRequest

//Find All Tasks for a particular User and Asset
def findWorkflowTasksRequest = new FindWorkflowTasksRequest()
findWorkflowTasksRequest.setUserId(string2Uuid(userIdReq))
findWorkflowTasksRequest.setBusinessItemId(assetId)

def tasksReq = workflowTaskApi.findWorkflowTasks(findWorkflowTasksRequest).getResults()

// Put the first Workflow Task ID in List 
def tasksList = [tasksReq.get(0).getId()]

// Put the Form prorperties of the Task in a Map
def taskFormPropertiesMap = [:]
taskFormPropertiesMap.put("approve", "true")
taskFormPropertiesMap.put("comment", "Approved")

// Call the CompleteWorkflowTaskRequest and pass the List of Workflow ID and the Map of the Form Properties
def completeWorkflowTasksRequest = CompleteWorkflowTasksRequest.builder()
.setTaskIds(tasksList)
.setTaskFormProperties(taskFormPropertiesMap)
.build()

def completedTaskList = workflowTaskApi.completeWorkflowTasks(completeWorkflowTasksRequest).getResults()

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Caused by: groovy.lang.MissingMethodException: No signature of method: com.collibra.dgc.core.api.dto.workflow.CompleteWorkflowTasksRequest$Builder.setTaskIds() is applicable for argument types: (ArrayList) values: [[018e3fc7-933e-7fef-8506-855012e1ff3e]]
Possible solutions: taskIds(java.util.List)

When you create a List in Groovy, it is defaulted to ArrayList. It is an implementing class of java.util.List.

Not sure where I am going wrong. Any pointers will be much appreciated.

Thanks