fix NPE when logging an exception without message. PR 47623.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@800678 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -420,6 +420,10 @@ Fixed bugs:
    failed to load.
    Bugzilla Report 44103.
 
+ * Logging exceptions without a message would cause a
+   NullPointerException.
+   Bugzilla Report 47623.
+
 Other changes:
 --------------
  * The get task now also follows redirects from http to https

src/main/org/apache/tools/ant/Project.java

@@ -2171,6 +2171,9 @@ public class Project implements ResourceFactory {
     private void fireMessageLoggedEvent(BuildEvent event, String message,
                                         int priority) {
 
+        if (message == null) {
+            message = String.valueOf(message);
+        }
         if (message.endsWith(StringUtils.LINE_SEP)) {
             int endIndex = message.length() - StringUtils.LINE_SEP.length();
             event.setMessage(message.substring(0, endIndex), priority);

src/tests/junit/org/apache/tools/ant/ProjectTest.java

@@ -276,6 +276,14 @@ public class ProjectTest extends TestCase {
         assertTrue("Expected logging thread to finish successfully", done[0]);
     }
 
+    /**
+     * @see https://issues.apache.org/bugzilla/show_bug.cgi?id=47623
+     */
+    public void testNullThrowableMessageLog() {
+        p.log(new Task() {}, null, new Throwable(), Project.MSG_ERR);
+        // be content if no exception has been thrown
+    }
+
     private class DummyTaskPrivate extends Task {
         public DummyTaskPrivate() {}
         public void execute() {}