title: detached entity passed to persist error while inserting a new record
body: <p>I tried to explain the issue as much as I can please do let me know if you need more info.</p>
  
  <p>Entity for the emphist table has a unique key which is set up like this</p>
  
  <pre><code>@Id
      @GeneratedValue(strategy = GenerationType.SEQUENCE, generator="EMP_SERIAL_GERERATOR")
      @SequenceGenerator(name="EMP_SERIAL_GERERATOR", sequenceName="EMP_SERIAL",  allocationSize=1)
      @Column(name="EMP_SERIAL", nullable=false, precision=9)
      private long empSerial;
  
  
  
  try {
              em.persist(EmphistNew);
          } catch (Exception e) {
              throw e;
          }
  </code></pre>
  
  <p>In the code, I am trying to persist a new record into my emphist table and I get the following error.</p>
  
  <p>javax.persistence.PersistenceException: org.hibernate.PersistentObjectException: detached entity passed to persist: com.company.dep.project.model.emphist
      at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1692) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
      at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1602) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
      at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1608) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
      at org.hibernate.jpa.spi.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:1152) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
      at com.company.dep.project.batch.process.CheckandfillgapProcessor.insertTransaction(CheckandfillgapProcessor.java:428) [classes/:na]
      at com.company.dep.project.batch.process.CheckandfillgapProcessor.checkForGaps(CheckandfillgapProcessor.java:247) [classes/:na]
      at com.company.dep.project.batch.process.CheckandfillgapProcessor.process(CheckandfillgapProcessor.java:103) [classes/:na]
      at com.company.dep.project.batch.process.test.CheckandfillgapProcessorTest.testCheckForGaps2(CheckandfillgapProcessorTest.java:129) [test-classes/:na]
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_51]
      at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_51]
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_51]
      at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_51]
      at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) [junit-4.12.jar:4.12]
      at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) [junit-4.12.jar:4.12]
      at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) [junit-4.12.jar:4.12]
      at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) [junit-4.12.jar:4.12]
      at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) [junit-4.12.jar:4.12]
      at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75) [spring-test-4.3.18.RELEASE.jar:4.3.18.RELEASE]
      at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27) [junit-4.12.jar:4.12]
      at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86) [spring-test-4.3.18.RELEASE.jar:4.3.18.RELEASE]
      at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84) [spring-test-4.3.18.RELEASE.jar:4.3.18.RELEASE]
      at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) [junit-4.12.jar:4.12]
      at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252) [spring-test-4.3.18.RELEASE.jar:4.3.18.RELEASE]
      at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94) [spring-test-4.3.18.RELEASE.jar:4.3.18.RELEASE]
      at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) [junit-4.12.jar:4.12]
      at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) [junit-4.12.jar:4.12]
      at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) [junit-4.12.jar:4.12]
      at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) [junit-4.12.jar:4.12]
      at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) [junit-4.12.jar:4.12]
      at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) [junit-4.12.jar:4.12]
      at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) [spring-test-4.3.18.RELEASE.jar:4.3.18.RELEASE]
      at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27) [junit-4.12.jar:4.12]
      at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) [spring-test-4.3.18.RELEASE.jar:4.3.18.RELEASE]
      at org.junit.runners.ParentRunner.run(ParentRunner.java:363) [junit-4.12.jar:4.12]
      at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191) [spring-test-4.3.18.RELEASE.jar:4.3.18.RELEASE]
      at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86) [.cp/:na]
      at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) [.cp/:na]
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459) [.cp/:na]
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678) [.cp/:na]
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382) [.cp/:na]
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192) [.cp/:na]
  Caused by: org.hibernate.PersistentObjectException: detached entity passed to persist:  com.company.dep.project.model.emphist
      at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:124) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
      at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:58) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
      at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:775) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
      at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:748) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
      at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:753) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
      at org.hibernate.jpa.spi.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:1146) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
      ... 37 common frames omitted</p>