.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>&nbsp;line)</span></div>
<div class="block">Add an RFC822 header line to the header store.
 If the line starts with a space or tab (a continuation line),
 add it to the last header line in the list.  Otherwise,
 append the new header line to the list.  <p>

 Note that RFC822 headers can only contain US-ASCII characters</div>
<dl class="notes">
<dt>Parameters:</dt>
<