Fix ClassCastException on getChangeToken after a ConcurrentUpdateException

 ERROR [Nuxeo-Work-elasticSearchIndexing-2:2865555041367.2094492134] [org.nuxeo.ecm.core.work.AbstractWork] Exception during work: IndexingWorker(61f81dca-b429-4161-9bec-6a24277b72f4, , Progress(?%, ?/0), null)
java.lang.ClassCastException: org.nuxeo.ecm.core.api.model.DeltaLong cannot be cast to java.lang.Long
	at org.nuxeo.ecm.core.storage.sql.coremodel.SQLDocumentLive.getChangeToken(SQLDocumentLive.java:329)
	at org.nuxeo.ecm.core.api.AbstractSession.getChangeToken(AbstractSession.java:2415)
	at org.nuxeo.ecm.core.api.impl.DocumentModelImpl.getChangeToken(DocumentModelImpl.java:1513)
	at org.nuxeo.ecm.automation.jaxrs.io.documents.JsonESDocumentWriter.writeSystemProperties(JsonESDocumentWriter.java:166)
	at org.nuxeo.ecm.automation.jaxrs.io.documents.JsonESDocumentWriter.writeDoc(JsonESDocumentWriter.java:108)
	at org.nuxeo.ecm.automation.jaxrs.io.documents.JsonESDocumentWriter.writeESDocument(JsonESDocumentWriter.java:236)
	at org.nuxeo.elasticsearch.core.ElasticSearchIndexingImpl.buildEsIndexingRequest(ElasticSearchIndexingImpl.java:416)
	at org.nuxeo.elasticsearch.core.ElasticSearchIndexingImpl.processBulkIndexCommands(ElasticSearchIndexingImpl.java:177)
	at org.nuxeo.elasticsearch.core.ElasticSearchIndexingImpl.indexNonRecursive(ElasticSearchIndexingImpl.java:146)
	at org.nuxeo.elasticsearch.ElasticSearchComponent.indexNonRecursive(ElasticSearchComponent.java:405)
	at org.nuxeo.elasticsearch.work.IndexingWorker.doIndexingWork(IndexingWorker.java:73)
	at org.nuxeo.elasticsearch.work.AbstractIndexingWorker.doWork(AbstractIndexingWorker.java:61)
	at org.nuxeo.elasticsearch.work.BaseIndexingWorker.work(BaseIndexingWorker.java:48)
	at org.nuxeo.ecm.core.work.AbstractWork.runWorkWithTransaction(AbstractWork.java:435)
	at org.nuxeo.ecm.core.work.AbstractWork.run(AbstractWork.java:355)
	at org.nuxeo.ecm.core.work.WorkHolder.run(WorkHolder.java:57)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)