Copy/pasting wiki attachment to template causes failure in save

2016-02-18 13:06:08,826 WARN [http-bio-8080-exec-3] [xhtml.editor.embed.EditorEmbeddedImageResourceUnmarshaller] unmarshal Error unmarshaling editor embedded image
 -- referer: http://localhost:8080/confluence/pages/templates2/createpagetemplate.action?key= | url: /confluence/pages/templates2/docreatepagetemplate.action | traceId: 7ce104360fdd84a6 | userName: ad
min | action: docreatepagetemplate
java.lang.IllegalArgumentException: Content must not be null
        at org.springframework.util.Assert.notNull(Assert.java:112)
        at com.atlassian.confluence.pages.attachments.CachingAttachmentDao.getLatestAttachment(CachingAttachmentDao.java:67)
        at com.atlassian.confluence.pages.DefaultAttachmentManager.getAttachment(DefaultAttachmentManager.java:125)
        at com.atlassian.confluence.pages.DefaultAttachmentManager.getAttachment(DefaultAttachmentManager.java:91)
        at com.atlassian.confluence.pages.DelegatorAttachmentManager.getAttachment(DelegatorAttachmentManager.java:101)
        at com.atlassian.confluence.pages.CachingAttachmentManager.getAttachment(CachingAttachmentManager.java:158)
        at sun.reflect.GeneratedMethodAccessor668.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
        at com.sun.proxy.$Proxy132.getAttachment(Unknown Source)
        at com.atlassian.confluence.content.render.xhtml.editor.embed.EditorEmbeddedImageResourceUnmarshaller.unmarshal(EditorEmbeddedImageResourceUnmarshaller.java:94)
        at com.atlassian.confluence.content.render.xhtml.editor.embed.EditorEmbeddedImageResourceUnmarshaller.unmarshal(EditorEmbeddedImageResourceUnmarshaller.java:41)
        at com.atlassian.confluence.content.render.xhtml.UnmarshalMarshalFragmentTransformer.transform(UnmarshalMarshalFragmentTransformer.java:28)
        at com.atlassian.confluence.content.render.xhtml.transformers.DefaultFragmentTransformer.transformFragment(DefaultFragmentTransformer.java:141)
        at com.atlassian.confluence.content.render.xhtml.transformers.DefaultFragmentTransformer.transform(DefaultFragmentTransformer.java:123)
        at com.atlassian.confluence.content.render.xhtml.editor.EditorXhtmlTransformer.transform(EditorXhtmlTransformer.java:45)
        at com.atlassian.confluence.content.render.xhtml.TransformerChain.transform(TransformerChain.java:33)
        at com.atlassian.confluence.content.render.xhtml.TransformerChain.transform(TransformerChain.java:33)
        at com.atlassian.confluence.content.render.xhtml.PluggableTransformerChain.transform(PluggableTransformerChain.java:39)
        at com.atlassian.confluence.content.render.xhtml.editor.DefaultEditorConverter.convert(DefaultEditorConverter.java:37)
        at com.atlassian.confluence.content.render.xhtml.DefaultFormatConverter.convertToStorageFormat(DefaultFormatConverter.java:123)
        at com.atlassian.confluence.plugins.templates.actions.CreatePageTemplateAction.createPageTemplate(CreatePageTemplateAction.java:36)
        at com.atlassian.confluence.plugins.templates.actions.CreatePageTemplateAction.execute(CreatePageTemplateAction.java:20)
        at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
        at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
        at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
        at com.atlassian.confluence.core.ConfluenceWorkflowInterceptor.intercept(ConfluenceWorkflowInterceptor.java:58)

Cause
javax.persistence.PersistenceException: org.hibernate.HibernateException: Unable to resolve entity name from Class [com.atlassian.confluence.content.render.xhtml.DefaultConversionContext$1] expected instance/subclass of [com.atlassian.confluence.core.ContentEntityObject]
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:149)

caused by: org.hibernate.HibernateException: Unable to resolve entity name from Class [com.atlassian.confluence.content.render.xhtml.DefaultConversionContext$1] expected instance/subclass of [com.atlassian.confluence.core.ContentEntityObject]
    at org.hibernate.tuple.entity.PojoEntityTuplizer.determineConcreteSubclassEntityName(PojoEntityTuplizer.java:316)

Stack Trace:[hide]
javax.persistence.PersistenceException: org.hibernate.HibernateException: Unable to resolve entity name from Class [com.atlassian.confluence.content.render.xhtml.DefaultConversionContext$1] expected instance/subclass of [com.atlassian.confluence.core.ContentEntityObject]
	at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:149)
	at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:157)
	at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:164)
	at com.atlassian.hibernate.util.SessionHelper.flushAllowNoTransaction(SessionHelper.java:83)
	at com.atlassian.confluence.core.persistence.hibernate.VersionedHibernateObjectDao.save(VersionedHibernateObjectDao.java:145)
	at jdk.internal.reflect.GeneratedMethodAccessor2218.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:198)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:295)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
	at com.sun.proxy.$Proxy125.save(Unknown Source)
	at com.atlassian.confluence.pages.templates.Defa