title: how to pass header values like username and password in http:outbound-endpoint mule
body: <pre><code>&lt;message-properties-transformer scope="outbound"&gt; 
      &lt;add-message-property key="username" value="admin" /&gt; 
      &lt;add-message-property key="password" value="admin"/&gt;
      &lt;add-message-property key="Accept" value="application/json"/&gt;
  &lt;/message-properties-transformer&gt;
  &lt;logger  message=" outbound header username and password... 
      #[message.outboundProperties['username']] and      
      #[message.outboundProperties['password']]"
   level="INFO" doc:name="Logger"/&gt; 
  
   &lt;http:outbound-endpoint 
         exchange-pattern="request-response"  
         address="http://localhost:8080/callReservation" 
         method="POST" 
         contentType="application/json" 
         doc:name="HTTP"/&gt;
  </code></pre>
  
  <p>Here i'm unable to pass header values to http outbound endpoint.any suggestions</p>
  
  <pre><code>&lt;http:outbound-endpoint exchange-pattern="request-response"  address="http://localhost:8080/callreservation" method="POST" contentType="application/json" doc:name="HTTP"&gt;
  </code></pre>
  
  <p>for this outbound endpoint , I try set username,password as headers</p>
  
  <p>like follows</p>
  
  <pre><code> &lt;message-properties-transformer scope="outbound"&gt; 
  &lt;add-message-property key="'http.headers'.username" value="admin"/&gt; 
  &lt;add-message-property key="'http.headers'password" value="admin"/&gt; 
  &lt;/message-properties-transformer&gt; 
  
  
  
  &lt;set-property propertyName="username" value="admin"/&gt;
  &lt;set-property propertyName="password" value="isgn@123"/&gt;
  &lt;set-property propertyName="Accept" value="application/json"/&gt;
  </code></pre>
  
  <p>but nothing accept as headers for outbound endpoint . Im using mule 3.6.0</p>
  
  <p>any suggestions</p>