Solr IndexerJob error displayed in console when connecting to XWiki on Oracle

2014-05-29 10:16:35,997 [XWiki Solr index job thread] ERROR o.x.s.s.i.j.IndexerJob         - Exception thrown during job execution
java.lang.NullPointerException: null
        at org.xwiki.search.solr.internal.job.DatabaseDocumentIterator.next(DatabaseDocumentIterator.java:130) ~[xwiki-platform-search-solr-api-6.1-milestone-1.jar:na]
        at org.xwiki.search.solr.internal.job.DatabaseDocumentIterator.next(DatabaseDocumentIterator.java:56) ~[xwiki-platform-search-solr-api-6.1-milestone-1.jar:na]
        at org.xwiki.search.solr.internal.job.DiffDocumentIterator.next(DiffDocumentIterator.java:117) ~[xwiki-platform-search-solr-api-6.1-milestone-1.jar:na]
        at org.xwiki.search.solr.internal.job.IndexerJob.updateSolrIndex(IndexerJob.java:111) ~[xwiki-platform-search-solr-api-6.1-milestone-1.jar:na]
        at org.xwiki.search.solr.internal.job.IndexerJob.runInternal(IndexerJob.java:94) ~[xwiki-platform-search-solr-api-6.1-milestone-1.jar:na]
        at org.xwiki.job.internal.AbstractJob.run(AbstractJob.java:155) ~[xwiki-commons-job-6.1-milestone-1.jar:na]
        at org.xwiki.context.concurrent.ExecutionContextRunnable.run(ExecutionContextRunnable.java:70) [xwiki-commons-context-6.1-milestone-1.jar:na]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [na:1.8.0_05]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [na:1.8.0_05]
        at java.lang.Thread.run(Unknown Source) [na:1.8.0_05]