NPE when using LiteAutoDetach 
------------------------------

                 Key: OPENJPA-2136
                 URL: https://issues.apache.org/jira/browse/OPENJPA-2136
             Project: OpenJPA
          Issue Type: Bug
          Components: kernel
    Affects Versions: 2.2.0, 2.1.1, 2.0.0, 2.3.0
            Reporter: Rick Curtis
            Assignee: Rick Curtis
             Fix For: 2.3.0, 2.2.1


I encountered a NPE[2] today when using the LiteAutoDetach[1] configuration property. The steps required to cause this problem is as follows:

- Configure LiteAutoDetach for your PU.
- Find a non-transactional Entity.
- Clear the EntityManager.
- Begin / commit transaction.

The problem is that LiteAutoDetach doesn't properly clean up the EntityManager while it is performing lite detachment. State is left in BrokerImpl._pending set which is then incorrectly used post em.clear. It also appears that there are a number of other BrokerImpl datastructures that *should* have been cleaned up on clear / detachall. 

[1] http://openjpa.apache.org/builds/latest/docs/docbook/manual.html#ref_guide_detach_state
[2] Caused by: <openjpa-2.2.0-SNAPSHOT-r422266:1244602 nonfatal general error> org.apache.openjpa.persistence.PersistenceException: null
	at org.apache.openjpa.kernel.BrokerImpl.beforeCompletion(BrokerImpl.java:1998)
	at org.apache.openjpa.kernel.LocalManagedRuntime.commit(LocalManagedRuntime.java:81)
	at org.apache.openjpa.kernel.BrokerImpl.commit(BrokerImpl.java:1514)
	at org.apache.openjpa.kernel.DelegatingBroker.commit(DelegatingBroker.java:933)
	at org.apache.openjpa.persistence.EntityManagerImpl.commit(EntityManagerImpl.java:570)
	... 24 more
Caused by: java.lang.NullPointerException
	at org.apache.openjpa.Customer.pcProvideField(Customer.java)
	at org.apache.openjpa.kernel.StateManagerImpl.provideField(StateManagerImpl.java:3161)
	at org.apache.openjpa.kernel.StateManagerImpl.preFlush(StateManagerImpl.java:2980)
	at org.apache.openjpa.kernel.PDirtyState.beforeFlush(PDirtyState.java:38)
	at org.apache.openjpa.kernel.StateManagerImpl.beforeFlush(StateManagerImpl.java:1053)
	at org.apache.openjpa.kernel.BrokerImpl.flush(BrokerImpl.java:2112)
	at org.apache.openjpa.kernel.BrokerImpl.flushSafe(BrokerImpl.java:2072)
	at org.apache.openjpa.kernel.BrokerImpl.beforeCompletion(BrokerImpl.java:1990)
	... 28 more

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