The <meta http-equiv>
tags are only used when the HTML file in question is been opened from a non-HTTP resource such as local disk file system (via file://
URI) and not when the HTML file in question is been opened from a real HTTP resource (via http://
URI). Instead, the real HTTP response headers as set via HttpServletResponse#setHeader()
are been used.
So, your concrete problem is caused because those <meta http-equiv>
tags are ignored.