### Question:
ResponseValues { public String getHeaderValue(String name) { String value = null; if (myHeader != null) { String key = name != null ? name.toLowerCase() : null; Collection<String> values = myHeader.get(key); if (values != null) { value = StringUtilities.join(",", values); } } return value; }  long getContentLength(); Map<String, Collection<String>> getHeader(); String getHeaderValue(String name); int getResponseCode(); String getResponseMessage(); void setContentLength(long contentLength); void setHeader(Map<String, ? extends Collection<String>> header); void setResponseCode(int responseCode); void setResponseMessage(String responseMessage); String getContentType(); @Override String toString();  }### Answer:
@Test public void testGetHeaderValue() { Map<String, Collection<String>> headerValues = New.map(); headerValues.put("headeR", New.list("headerValue")); headerValues.put("header2", New.list("header2Value1", "header2Value2")); headerValues.put("Content-Type", New.list("ct")); ResponseValues response = new ResponseValues(); response.setHeader(headerValues); assertEquals("headerValue", response.getHeaderValue("Header")); assertEquals("header2Value1,header2Value2", response.getHeaderValue("header2")); assertEquals("ct", response.getContentType()); assertNull(response.getHeaderValue("header3")); }