Return empty collection for blank searches.

git-svn-id: http://svn.igniterealtime.org/svn/repos/messenger/trunk@1483 b35dd754-fafc-0310-a699-88a17e54d16e

src/java/org/jivesoftware/messenger/user/DefaultUserProvider.java

@@ -391,6 +391,9 @@ public class DefaultUserProvider implements UserProvider {
         if (!getSearchFields().containsAll(fields)) {
             throw new IllegalArgumentException("Search fields " + fields + " are not valid.");
         }
+        if (query == null || "".equals(query)) {
+            return Collections.emptyList();
+        }
         // SQL LIKE queries don't map directly into a keyword/wildcard search like we want.
         // Therefore, we do a best approximiation by replacing '*' with '%' and then
         // surrounding the whole query with two '%'. This will return more data than desired,
@@ -453,6 +456,9 @@ public class DefaultUserProvider implements UserProvider {
         if (!getSearchFields().containsAll(fields)) {
             throw new IllegalArgumentException("Search fields " + fields + " are not valid.");
         }
+        if (query == null || "".equals(query)) {
+            return Collections.emptyList();
+        }
         // SQL LIKE queries don't map directly into a keyword/wildcard search like we want.
         // Therefore, we do a best approximiation by replacing '*' with '%' and then
         // surrounding the whole query with two '%'. This will return more data than desired,