code: public List<FacesMessage> getMessageList(String clientId) {
          if (defaultFacesContext != null) {
              return defaultFacesContext.getMessageList(clientId);
          }
          throw new UnsupportedOperationException();
      }
docs: <p class="changed_added_2_0">Like {@link
  #getMessages(java.lang.String)}, but returns a
  <code>List&lt;FacesMessage&gt;</code> of messages for the
  component with client id matching argument
  <code>clientId</code>.</p>
  
  <p>The default implementation throws
  <code>UnsupportedOperationException</code> and is provided
  for the sole purpose of not breaking existing applications that extend
  this class.</p>
  
  @return an immutable <code>List</code> which is effectively a snapshot
  of the messages present at the time of invocation.
  
  @throws IllegalStateException if this method is called after
  this instance has been released
  
  @since 2.0