@Override
protected String getResponseBodyFrameTrace(int streamId, String body) {
    if (testData.getExpectedStatus() == 200) {
        return super.getResponseBodyFrameTrace(streamId, body);
    } else if (testData.getExpectedStatus() == 400) {
        /*
         * Need to be careful here. The test wants the exact content length
         * in bytes.
         * This will vary depending on where the test is run due to:
         * - The length of the version string that appears once in the error
         *   page
         * - The status header uses a UTF-8 EN dash. When running in an IDE
         *   the UTF-8 properties files will be used directly rather than
         *   after native2ascii conversion.
         *
         * Note: The status header appears twice in the error page.
         */
        int serverInfoLength = ServerInfo.getServerInfo().getBytes().length;
        StringManager sm = StringManager.getManager(
                ErrorReportValve.class.getPackage().getName(), Locale.ENGLISH);
        String reason = sm.getString("http." + testData.getExpectedStatus() + ".reason");
        int descriptionLength = sm.getString("http." + testData.getExpectedStatus() + ".desc")
                .getBytes(StandardCharsets.UTF_8).length;
        int statusHeaderLength = sm
                .getString("errorReportValve.statusHeader",
                        String.valueOf(testData.getExpectedStatus()), reason)
                .getBytes(StandardCharsets.UTF_8).length;
        int typeLabelLength = sm.getString("errorReportValve.type")
                .getBytes(StandardCharsets.UTF_8).length;
        int statusReportLabelLength = sm.getString("errorReportValve.statusReport")
                .getBytes(StandardCharsets.UTF_8).length;
        int descriptionLabelLength = sm.getString("errorReportValve.description")
                .getBytes(StandardCharsets.UTF_8).length;
        // 196 bytes is the static length of the pure HTML code from the ErrorReportValve
        int len = 196 + org.apache.catalina.util.TomcatCSS.TOMCAT_CSS
                .getBytes(StandardCharsets.UTF_8).length +
                typeLabelLength + statusReportLabelLength + descriptionLabelLength +
                descriptionLength + serverInfoLength + statusHeaderLength * 2;
        String contentLength = String.valueOf(len);
        return getResponseBodyFrameTrace(streamId,
                testData.getExpectedStatus(), "text/html;charset=utf-8",
                "en", contentLength, contentLength);
    } else {
        Assert.fail();
        // To keep the IDE happy
        return null;
    }
}