s="block">Get all the headers for this header name. Returns <code>null</code>
 if no headers for this header name are available.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>header_name</code> - the name of this header</dd>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>the value fields for all headers with 
                                this name</dd>
<dt><span class="throwsLabel">Throws:</span></dt>
<dd><code><a href="MessagingException.html" title="class in jakarta.