final String headerName = "key";
final String headerVal1 = "value1";
final String headerVal2 = "value2";
final String headerValue = headerVal1 + ", ," + headerVal2;
final RestMessage msg = new RestResponseBuilder()
.addHeaderValue(headerName, headerValue)
.build();
Assert.assertEquals(headerValue, msg.getHeader(headerName));
Assert.assertEquals(Arrays.asList(headerVal1, headerVal2), msg.getHeaderValues(headerName));