/**
     * Gets the value of the specified header.
     *
     * @param name the name of the header.
     * @return the header value, or null if the header does not exist.
     */
    public String getHeaderValue(final String name) {
        final String[] values = getHeaderValues(name);
        if (values.length == 0) {
            return null;
        }
        return values[0];
    }

        assertEquals(429, mockResponse.getStatus());
        assertEquals("application/json;charset=UTF-8", mockResponse.getContentType());
        assertEquals("60", mockResponse.getHeaderValue("Retry-After"));
        assertTrue(mockResponse.getWriterOutput().contains("\"status\":9"));
        assertTrue(mockResponse.getWriterOutput().contains("\"retry_after\":60"));
    }

    @Test

        assertEquals("application/json", response.getHeaderValue("content-type"));
        assertEquals("application/json", response.getHeaderValue("CONTENT-TYPE"));
        assertEquals("application/json", response.getHeaderValue("Content-Type"));

        assertEquals("100", response.getHeaderValue("content-length"));
        assertEquals("100", response.getHeaderValue("CONTENT-LENGTH"));

                response.setStatus(curlResponse.getHttpStatusCode());
                writeHeaders(response);
                final String responseContentType = curlResponse.getHeaderValue("Content-Type");
                if (StringUtil.isBlank(responseContentType)) {
                    response.setHeader("Content-Type", "application/json");
                } else {