Fix potential NPE in mailers, remove root cause of NPE reported in PR 44009.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@704496 13f79535-47bb-0310-9956-ffa450edef68

WHATSNEW

@@ -244,6 +244,9 @@ Fixed bugs:
    worked if JavaMail was available.
    Bugzilla Report 42389.
 
+ * MailLogger could cause a NullPointerException.
+   Bugzilla Report 44009.
+
 Other changes:
 --------------
 

src/main/org/apache/tools/ant/listener/MailLogger.java

@@ -355,6 +355,7 @@ public class MailLogger extends DefaultLogger {
         mailer.setBccList(new Vector());
         mailer.setFiles(new Vector());
         mailer.setSubject(values.subject());
+        mailer.setHeaders(new Vector());
         mailer.send();
     }
     private Vector vectorizeEmailAddresses(String listString) {

src/main/org/apache/tools/ant/taskdefs/email/MimeMailer.java

@@ -202,10 +202,12 @@ public class MimeMailer extends Mailer {
             }
             msg.addHeader("Date", getDate());
 
+            if (headers != null) {
             for (Iterator iter = headers.iterator(); iter.hasNext();) {
                 Header h = (Header) iter.next();
                 msg.addHeader(h.getName(), h.getValue());
             }
+            }
             PrintStream out = new PrintStream(sds.getOutputStream());
             message.print(out);
             out.close();

src/main/org/apache/tools/ant/taskdefs/email/PlainMailer.java

@@ -71,11 +71,13 @@ class PlainMailer extends Mailer {
             } else {
                 mailMessage.setHeader("Content-Type", message.getMimeType());
             }
+            if (headers != null) {
             e = headers.elements();
             while (e.hasMoreElements()) {
                 Header h = (Header) e.nextElement();
                 mailMessage.setHeader(h.getName(), h.getValue());
             }
+            }
             PrintStream out = mailMessage.getPrintStream();
             message.print(out);