Redirect URLs use wrong character encoding (ISO-8859-1 instead of UTF-8)

When redirecting to a new url using org.eclipse.jetty.server.Response.sendRedirect(String)
the url string is encoded using ISO-8859-1 instead of UTF-8.

This leads to invalid urls being sent to the redirect target. If this is also a Jetty,
url parsing fails at Utf8StringBuilder:line 119 because of invalid utf-8 bytes.

The problem seems to be
BufferCache$CachedBuffer(ByteArrayBuffer).<init>(String) line: 73

where StringUtil.getBytes is used, instead of the variant with proper UTF-8 encoding

Here's the stack leading to that code:

BufferCache$CachedBuffer(ByteArrayBuffer).<init>(String) line: 73
BufferCache$CachedBuffer(ByteArrayBuffer$CaseInsensitive).<init>(String) line: 420
BufferCache$CachedBuffer.<init>(String, int) line: 120
HttpHeaderValues(BufferCache).lookup(String) line: 93
HttpFields.put(String, String) line: 575
Response.setHeader(String, String) line: 482
Response.sendRedirect(String) line: 443

To reproduce, redirect to a different url using
javax.servlet.http.HttpServletResponse.sendRedirect(String)
with the string containing special chars, such as umlauts (äöü)
or any other ISO-8859-1 character above 127.