fix NPE GSAresponseWriter on query=null

java.lang.NullPointerException
	at net.yacy.cora.federate.solr.responsewriter.GSAResponseWriter.highlight(GSAResponseWriter.java:328)
	at net.yacy.cora.federate.solr.responsewriter.GSAResponseWriter.write(GSAResponseWriter.java:263)
	at net.yacy.http.servlets.SolrServlet.service(SolrServlet.java:235)

source/net/yacy/cora/federate/solr/responsewriter/GSAResponseWriter.java

@@ -325,6 +325,7 @@ public class GSAResponseWriter implements QueryResponseWriter {
     }
 
     public static String highlight(String text, String query) {
+        if (query != null) {
             String[] q = CommonPattern.SPACE.split(CommonPattern.PLUS.matcher(query.trim().toLowerCase()).replaceAll(" "));
             for (String s: q) {
                 int p = text.toLowerCase().indexOf(s.toLowerCase());
@@ -333,4 +334,6 @@ public class GSAResponseWriter implements QueryResponseWriter {
             }
             return text.replaceAll(Pattern.quote("</b> <b>"), " ");
         } 
+        return text;
+    }
 }