JavaTest Agents (passive and active) accept zero concurrency value and throw IllegalArgumentException.
How to reproduce:
1. Start JavaTest Agent
2. Set concurrency value to zero
3. Click on Start button
No error or warning will be shown but exception is thrown in command line:
Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: bad concurrency: 0
        at com.sun.javatest.agent.Agent.<init>(Agent.java:161)
        at com.sun.javatest.agent.AgentPanel$ParamPanel.createAgent(AgentPanel.java:854)
        at com.sun.javatest.agent.AgentPanel.start(AgentPanel.java:164)
        at com.sun.javatest.agent.AgentPanel$ButtonPanel.actionPerformed(AgentPanel.java:511)
        at java.awt.Button.processActionEvent(Button.java:409)
        at java.awt.Button.processEvent(Button.java:377)
        at java.awt.Component.dispatchEventImpl(Component.java:4866)
        at java.awt.Component.dispatchEvent(Component.java:4691)
        at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:703)
        at java.awt.EventQueue.access$000(EventQueue.java:102)
        at java.awt.EventQueue$3.run(EventQueue.java:662)
        at java.awt.EventQueue$3.run(EventQueue.java:660)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
        at java.awt.EventQueue$4.run(EventQueue.java:676)
        at java.awt.EventQueue$4.run(EventQueue.java:674)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:673)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:216)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:135)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:123)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:119)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:111)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)