This is a markup inline filter.
It assumes that {@link org.apache.wicket.markup.parser.filter.WicketTagIdentifier}has been called first and search for a <head> tag (note: not wicket:head). Provided the markup contains a <body> tag it will automatically prepend a <head> tag if missing.
Additionally this filter handles <wicket:header-items/>. If there is such tag then it is marked as the one that should be used as {@link org.apache.wicket.markup.html.internal.HtmlHeaderContainer}, by setting its id to {@value #HEADER_ID}.
Note: This handler is only relevant for Pages (see MarkupParser.newFilterChain())
@see org.apache.wicket.markup.MarkupParser
@see org.apache.wicket.markup.resolver.HtmlHeaderResolver
@author Juergen Donnerstag