getHeaders returns a Map<String, String> - not need to call toString on a String object

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/email/trunk@1507612 13f79535-47bb-0310-9956-ffa450edef68
Remove redundant initialization

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/email/trunk@1507613 13f79535-47bb-0310-9956-ffa450edef68