Why jBPM6 task server complains "There are no known Business Administrators, task cannot be created according to WS-HT specification" ?

Issue

• While working with User Tasks the jBPM6 Task Server throws the following ERROR. How to fix it?

Error when creating task on task server for work item id xxxxx. Error reported by task server: There are no known Business Administrators, task cannot be created according to WS-HT specification
org.jbpm.services.task.exception.CannotAddTaskException: There are no known Business Administrators, task cannot be created according to WS-HT specification
    at org.jbpm.services.task.commands.UserGroupCallbackTaskCommand.doCallbackOperationForPeopleAssignments(UserGroupCallbackTaskCommand.java:232) [jbpm-human-task-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.services.task.commands.AddTaskCommand.execute(AddTaskCommand.java:100) [jbpm-human-task-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.services.task.commands.AddTaskCommand.execute(AddTaskCommand.java:53) [jbpm-human-task-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.services.task.commands.TaskCommandExecutorImpl$SelfExecutionCommandService.execute(TaskCommandExecutorImpl.java:65) [jbpm-human-task-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41) [drools-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.services.task.persistence.TaskTransactionInterceptor.execute(TaskTransactionInterceptor.java:54) [jbpm-human-task-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.services.task.commands.TaskCommandExecutorImpl.execute(TaskCommandExecutorImpl.java:40) [jbpm-human-task-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.services.task.impl.command.CommandBasedTaskService.addTask(CommandBasedTaskService.java:471) [jbpm-human-task-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.services.task.wih.LocalHTWorkItemHandler.executeWorkItem(LocalHTWorkItemHandler.java:61) [jbpm-human-task-workitems-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.persistence.jpa.processinstance.JPAWorkItemManager.internalExecuteWorkItem(JPAWorkItemManager.java:56) [drools-persistence-jpa-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.workflow.instance.node.WorkItemNodeInstance.internalTrigger(WorkItemNodeInstance.java:124) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:155) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerNodeInstance(NodeInstanceImpl.java:337) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:296) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.workflow.instance.node.StartNodeInstance.triggerCompleted(StartNodeInstance.java:66) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.workflow.instance.node.StartNodeInstance.internalTrigger(StartNodeInstance.java:43) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:155) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.ruleflow.instance.RuleFlowProcessInstance.internalStart(RuleFlowProcessInstance.java:35) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.process.instance.impl.ProcessInstanceImpl.start(ProcessInstanceImpl.java:226) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.workflow.instance.impl.WorkflowProcessInstanceImpl.start(WorkflowProcessInstanceImpl.java:362) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.process.instance.ProcessRuntimeImpl.startProcessInstance(ProcessRuntimeImpl.java:194) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:176) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:168) [jbpm-flow-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.core.common.AbstractWorkingMemory.startProcess(AbstractWorkingMemory.java:1575) [drools-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.startProcess(StatefulKnowledgeSessionImpl.java:366) [drools-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.core.command.runtime.process.StartProcessCommand.execute(StartProcessCommand.java:121) [drools-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.core.command.runtime.process.StartProcessCommand.execute(StartProcessCommand.java:40) [drools-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.core.command.impl.DefaultCommandService.execute(DefaultCommandService.java:36) [drools-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41) [drools-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.persistence.SingleSessionCommandService$TransactionInterceptor.execute(SingleSessionCommandService.java:533) [drools-persistence-jpa-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41) [drools-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.persistence.jpa.OptimisticLockRetryInterceptor.execute(OptimisticLockRetryInterceptor.java:73) [drools-persistence-jpa-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.persistence.SingleSessionCommandService.execute(SingleSessionCommandService.java:377) [drools-persistence-jpa-6.0.3-redhat-4.jar:6.0.3-redhat-4]
    at org.drools.core.command.impl.CommandBasedStatefulKnowledgeSession.startProcess(CommandBasedStatefulKnowledgeSession.java:232) [drools-core-6.0.3-redhat-4.jar:6.0.3-redhat-4]

• The DBUserGroupCallbackImplTest class [1] does not show any information for inserting Administrators and Administrator group and user information into the database.
  How does these user and group make their way into the back end database?

[1] DBUserGroupCallbackImplTest.java