User index not working when using Korean language

org.w3c.dom.DOMException: INVALID_CHARACTER_ERR: An invalid or illegal XML character is specified. 
	at org.apache.xerces.dom.CoreDocumentImpl.createAttribute(Unknown Source)
	at org.apache.xerces.dom.ElementImpl.setAttribute(Unknown Source)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:243)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:247)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:247)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:247)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:247)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:247)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:247)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:247)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:247)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:247)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createSubnodes(XWikiDOMSerializer.java:247)
	at org.xwiki.xml.internal.html.XWikiDOMSerializer.createDOM(XWikiDOMSerializer.java:109)
	at org.xwiki.xml.internal.html.DefaultHTMLCleaner.clean(DefaultHTMLCleaner.java:159)
	at org.xwiki.rendering.internal.macro.html.HTMLMacro.cleanHTML(HTMLMacro.java:189)
	at org.xwiki.rendering.internal.macro.html.HTMLMacro.execute(HTMLMacro.java:159)
	at org.xwiki.rendering.internal.macro.html.HTMLMacro.execute(HTMLMacro.java:73)
	at org.xwiki.rendering.internal.transformation.macro.MacroTransformation.transform(MacroTransformation.java:252)
	at org.xwiki.rendering.internal.transformation.DefaultRenderingContext.transformInContext(DefaultRenderingContext.java:183)
	at org.xwiki.rendering.internal.transformation.DefaultTransformationManager.performTransformations(DefaultTransformationManager.java:94)
	at org.xwiki.display.internal.DocumentContentDisplayer.display(DocumentContentDisplayer.java:252)
	at org.xwiki.display.internal.DocumentContentDisplayer.display(DocumentContentDisplayer.java:125)
	at org.xwiki.display.internal.DocumentContentDisplayer.display(DocumentContentDisplayer.java:55)
	at org.xwiki.display.internal.DefaultDocumentDisplayer.display(DefaultDocumentDisplayer.java:96)
	at org.xwiki.display.internal.DefaultDocumentDisplayer.display(DefaultDocumentDisplayer.java:39)
	at org.xwiki.sheet.internal.SheetDocumentDisplayer.display(SheetDocumentDisplayer.java:113)
	at org.xwiki.sheet.internal.SheetDocumentDisplayer.display(SheetDocumentDisplayer.java:50)
	at org.xwiki.display.internal.ConfiguredDocumentDisplayer.display(ConfiguredDocumentDisplayer.java:67)
	at org.xwiki.display.internal.ConfiguredDocumentDisplayer.display(ConfiguredDocumentDisplayer.java:41)
	at com.xpn.xwiki.doc.XWikiDocument.getRenderedContent(XWikiDocument.java:1104)
	at com.xpn.xwiki.doc.XWikiDocument.getRenderedContent(XWikiDocument.java:1082)
	at com.xpn.xwiki.doc.XWikiDocument.getRenderedContent(XWikiDocument.java:1114)
	at com.xpn.xwiki.api.Document.getRenderedContent(Document.java:682)
	at sun.reflect.GeneratedMethodAccessor327.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(UberspectImpl.java:395)
	at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:384)
	at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:173)
	at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:280)
	at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:567)
	at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:71)
	at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:142)
	at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
	at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
	at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:106)
	at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
	at org.xwiki.velocity.introspection.TryCatchDirective.render(TryCatchDirective.java:72)
	at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:207)
	at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
	at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluateInternal(DefaultVelocityEngine.java:256)
	at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:222)
	at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:198)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.evaluateContent(InternalTemplateManager.java:713)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:613)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:594)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:563)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:549)
	at com.xpn.xwiki.internal.template.DefaultTemplateManager.render(DefaultTemplateManager.java:65)
	at com.xpn.xwiki.XWiki.evaluateTemplate(XWiki.java:1767)
	at com.xpn.xwiki.XWiki.parseTemplate(XWiki.java:1739)
	at com.xpn.xwiki.api.XWiki.parseTemplate(XWiki.java:797)
	at sun.reflect.GeneratedMethodAccessor176.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(UberspectImpl.java:395)
	at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:384)
	at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:173)
	at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:280)
	at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:369)
	at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
	at org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:216)
	at org.apache.velocity.runtime.directive.RuntimeMacro.render(RuntimeMacro.java:311)
	at org.apache.velocity.runtime.directive.RuntimeMacro.render(RuntimeMacro.java:230)
	at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:207)
	at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
	at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:87)
	at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
	at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
	at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:106)
	at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
	at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluateInternal(DefaultVelocityEngine.java:256)
	at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:222)
	at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:198)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.evaluateContent(InternalTemplateManager.java:713)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:613)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:594)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:563)
	at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:549)
	at com.xpn.xwiki.internal.template.DefaultTemplateManager.render(DefaultTemplateManager.java:65)
	at com.xpn.xwiki.XWiki.evaluateTemplate(XWiki.java:1767)
	at com.xpn.xwiki.web.Utils.parseTemplate(Utils.java:180)
	at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:355)
	at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:146)
	at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:425)
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:228)
	at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
	at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:449)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:769)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1667)
	at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:115)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
	at org.xwiki.wysiwyg.server.filter.ConversionFilter.doFilter(ConversionFilter.java:127)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
	at org.xwiki.container.servlet.filters.internal.SetHTTPHeaderFilter.doFilter(SetHTTPHeaderFilter.java:63)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
	at com.xpn.xwiki.plugin.webdav.XWikiDavFilter.doFilter(XWikiDavFilter.java:66)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
	at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:208)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
	at org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:111)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:583)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:577)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1125)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1059)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:215)
	at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:110)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
	at org.eclipse.jetty.server.Server.handle(Server.java:497)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:311)
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:248)
	at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:540)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:610)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:539)
	at java.lang.Thread.run(Thread.java:745)