Return "" for empty html

src/main/java/org/genesys2/server/service/impl/JsoupHtmlConverter.java

@@ -16,6 +16,7 @@
 
 package org.genesys2.server.service.impl;
 
+import org.apache.commons.lang.StringUtils;
 import org.genesys2.server.service.HtmlConverter;
 import org.jsoup.Jsoup;
 import org.jsoup.helper.StringUtil;
@@ -43,6 +44,9 @@ public class JsoupHtmlConverter implements HtmlConverter {
 	@Override
 	@Cacheable(value = "htmltotextcache", key = "#html", unless = "#result == null")
 	public String toText(String html) {
+		if (StringUtils.isBlank(html)) {
+			return StringUtils.EMPTY;
+		}
 		Document doc = Jsoup.parseBodyFragment(html);
 		return getPlainText(doc);
 	}