also added the same feature to the trigger.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@1159 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/resources/hudson/model/Project/configure-entries.jelly

@@ -87,7 +87,8 @@
                      checked="${!empty(up)}">
       <f:entry title="Projects names"
                description="Multiple projects can be specified like 'abc, def'">
-        <input class="setting-input" name="upstreamProjects"
+        <input class="setting-input validated" name="upstreamProjects"
+          checkUrl="'${rootURL}/publisher/BuildTrigger/check?value='+this.value"
           type="text" value="${h.getProjectListString(up)}"/>
       </f:entry>
     </f:optionalBlock>