@Test(expected=NullPointerException.class)
public void addHeaderMethodShouldThrowNpeWhenValueIsNull() {

	// Given
	String key = "test";
	String nullValue = null;
	
	String url = "test";
	HttpMethod method = HttpMethod.GET;
	HttpContent httpContent = new HttpContent(url, method);
	
	// When & Then
	httpContent.addHeader(key, nullValue);
}