@Override
    protected boolean isEnable(HttpMessageContainer httpMessageContainer) {
        if (httpMessageContainer instanceof SelectableHistoryReferencesContainer
                || httpMessageContainer instanceof SingleHistoryReferenceContainer) {
            return true;
        }
        return false;
    }
@ Override protected boolean isEnable ( HttpMessageContainer httpMessageContainer ) { if ( httpMessageContainer instanceof SelectableHistoryReferencesContainer || httpMessageContainer instanceof SingleHistoryReferenceContainer ) { return true ; } return false ; }
Tells whether or not the menu is enable for the given HTTP message container.
<p>
By default is enable for {@code SingleHistoryReferenceContainer}s and {@code SelectableHistoryReferencesContainer}s.
</p>
<p>
Normally overridden if other implementations of {@code HttpMessageContainer} are supported. The methods
{@code getSelectedMessages(HttpMessageContainer)}, {@code getSelectedHistoryReferences(HttpMessageContainer)} and
{@code getNumberOfSelectedMessages(HttpMessageContainer)} might need to be overridden accordingly to the supported
implementations.
</p>

@param httpMessageContainer the message container that will be evaluated
@return {@code true} if the given message container is a {@code SingleHistoryReferenceContainer} or
{@code SelectableHistoryReferencesContainer}.
@see #getSelectedMessages(HttpMessageContainer)
@see #getSelectedHistoryReferences(HttpMessageContainer)
@see #getNumberOfSelectedMessages(HttpMessageContainer)
@see SingleHistoryReferenceContainer
@see SelectableHistoryReferencesContainer