java.lang.ClassCastException in Solr indexer when having a white space in the list of supported languages

2016-01-25 14:14:32,866 [http://127.0.0.1:8080/xwiki/bin/saveandcontinue/XWiki/XWikiPreferences] ERROR rIndexAvailableLocalesListener - Failed to handle event [org.xwiki.bridge.event.DocumentUpdatedEvent@bb170136] with source [XWiki.XWikiPreferences] 
org.apache.solr.client.solrj.SolrServerException: java.lang.RuntimeException: java.lang.ClassCastException: org.apache.lucene.document.Field cannot be cast to java.lang.String
	at org.apache.solr.client.solrj.embedded.EmbeddedSolrServer.request(EmbeddedSolrServer.java:240) ~[solr-core-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:15]
	at org.apache.solr.client.solrj.SolrRequest.process(SolrRequest.java:135) ~[solr-solrj-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:17]
	at org.apache.solr.client.solrj.SolrClient.queryAndStreamResponse(SolrClient.java:1021) ~[solr-solrj-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:17]
	at org.apache.solr.client.solrj.SolrClient.queryAndStreamResponse(SolrClient.java:1046) ~[solr-solrj-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:17]
	at org.xwiki.search.solr.internal.AbstractSolrInstance.queryAndStreamResponse(AbstractSolrInstance.java:127) ~[xwiki-platform-search-solr-api-7.4.jar:na]
	at org.xwiki.search.solr.internal.SolrIndexAvailableLocalesListener.onEvent(SolrIndexAvailableLocalesListener.java:178) ~[xwiki-platform-search-solr-api-7.4.jar:na]
	at org.xwiki.observation.internal.DefaultObservationManager.notify(DefaultObservationManager.java:304) [xwiki-commons-observation-local-7.4.jar:na]
	at org.xwiki.observation.internal.DefaultObservationManager.notify(DefaultObservationManager.java:269) [xwiki-commons-observation-local-7.4.jar:na]
	at com.xpn.xwiki.XWiki.saveDocument(XWiki.java:1586) [xwiki-platform-legacy-oldcore-7.4.jar:na]
	at com.xpn.xwiki.web.SaveAction.save(SaveAction.java:181) [xwiki-platform-legacy-oldcore-7.4.jar:na]
	at com.xpn.xwiki.web.SaveAndContinueAction.doWrappedAction(SaveAndContinueAction.java:98) [xwiki-platform-legacy-oldcore-7.4.jar:na]
	at com.xpn.xwiki.web.SaveAndContinueAction.action(SaveAndContinueAction.java:195) [xwiki-platform-legacy-oldcore-7.4.jar:na]
	at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:416) [xwiki-platform-legacy-oldcore-7.4.jar:na]
	at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:184) [xwiki-platform-legacy-oldcore-7.4.jar:na]
	at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:425) [struts-core-1.3.10.jar:1.3.10]
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:228) [struts-core-1.3.10.jar:1.3.10]
	at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913) [struts-core-1.3.10.jar:1.3.10]
	at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462) [struts-core-1.3.10.jar:1.3.10]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:707) [javax.servlet-api-3.1.0.jar:3.1.0]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) [javax.servlet-api-3.1.0.jar:3.1.0]
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:808) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1669) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:115) [xwiki-platform-legacy-oldcore-7.4.jar:na]
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.xwiki.wysiwyg.server.filter.ConversionFilter.doFilter(ConversionFilter.java:127) [xwiki-platform-wysiwyg-server-7.4.jar:na]
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.xwiki.container.servlet.filters.internal.SetHTTPHeaderFilter.doFilter(SetHTTPHeaderFilter.java:63) [xwiki-platform-container-servlet-7.4.jar:na]
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at com.xpn.xwiki.plugin.webdav.XWikiDavFilter.doFilter(XWikiDavFilter.java:66) [xwiki-platform-webdav-server-7.4.jar:na]
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:208) [xwiki-platform-container-servlet-7.4.jar:na]
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:111) [xwiki-platform-container-servlet-7.4.jar:na]
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.xwiki.resource.servlet.RoutingFilter.doFilter(RoutingFilter.java:137) [xwiki-platform-resource-servlet-7.4.jar:na]
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:585) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:577) [jetty-security-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1127) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515) [jetty-servlet-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1061) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:215) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:110) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.Server.handle(Server.java:499) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:310) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:257) [jetty-server-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:540) [jetty-io-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:635) [jetty-util-9.2.13.v20150730.jar:9.2.13.v20150730]
	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:555) [jetty-util-9.2.13.v20150730.jar:9.2.13.v20150730]
	at java.lang.Thread.run(Thread.java:745) [na:1.8.0_66]
Caused by: java.lang.RuntimeException: java.lang.ClassCastException: org.apache.lucene.document.Field cannot be cast to java.lang.String
	at org.apache.solr.client.solrj.embedded.EmbeddedSolrServer.request(EmbeddedSolrServer.java:230) ~[solr-core-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:15]
	... 54 common frames omitted
Caused by: java.lang.ClassCastException: org.apache.lucene.document.Field cannot be cast to java.lang.String
	at org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.getWikiReference(SolrEntityReferenceResolver.java:93) ~[xwiki-platform-search-solr-api-7.4.jar:na]
	at org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.getEntityReference(SolrEntityReferenceResolver.java:70) ~[xwiki-platform-search-solr-api-7.4.jar:na]
	at org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.resolve(SolrEntityReferenceResolver.java:63) ~[xwiki-platform-search-solr-api-7.4.jar:na]
	at org.xwiki.search.solr.internal.reference.SolrEntityReferenceResolver.resolve(SolrEntityReferenceResolver.java:46) ~[xwiki-platform-search-solr-api-7.4.jar:na]
	at org.xwiki.search.solr.internal.reference.SolrDocumentReferenceResolver.resolve(SolrDocumentReferenceResolver.java:48) ~[xwiki-platform-search-solr-api-7.4.jar:na]
	at org.xwiki.search.solr.internal.reference.SolrDocumentReferenceResolver.resolve(SolrDocumentReferenceResolver.java:38) ~[xwiki-platform-search-solr-api-7.4.jar:na]
	at org.xwiki.search.solr.internal.SolrIndexAvailableLocalesListener$1.streamSolrDocument(SolrIndexAvailableLocalesListener.java:169) ~[xwiki-platform-search-solr-api-7.4.jar:na]
	at org.apache.solr.client.solrj.embedded.EmbeddedSolrServer$2.writeSolrDocument(EmbeddedSolrServer.java:208) ~[solr-core-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:15]
	at org.apache.solr.response.BinaryResponseWriter$Resolver.writeResultsBody(BinaryResponseWriter.java:124) ~[solr-core-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:15]
	at org.apache.solr.client.solrj.embedded.EmbeddedSolrServer$1.writeResults(EmbeddedSolrServer.java:198) ~[solr-core-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:15]
	at org.apache.solr.response.BinaryResponseWriter$Resolver.resolve(BinaryResponseWriter.java:86) ~[solr-core-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:15]
	at org.apache.solr.common.util.JavaBinCodec.writeVal(JavaBinCodec.java:182) ~[solr-solrj-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:17]
	at org.apache.solr.common.util.JavaBinCodec.writeNamedList(JavaBinCodec.java:166) ~[solr-solrj-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:17]
	at org.apache.solr.common.util.JavaBinCodec.writeKnownType(JavaBinCodec.java:266) ~[solr-solrj-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:17]
	at org.apache.solr.common.util.JavaBinCodec.writeVal(JavaBinCodec.java:171) ~[solr-solrj-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:17]
	at org.apache.solr.common.util.JavaBinCodec.marshal(JavaBinCodec.java:114) ~[solr-solrj-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:17]
	at org.apache.solr.client.solrj.embedded.EmbeddedSolrServer.request(EmbeddedSolrServer.java:204) ~[solr-core-5.3.1.jar:5.3.1 1703449 - noble - 2015-09-17 01:48:15]
	... 54 common frames omitted