fix nullable header/timeout/url arg

src/main/java/com/imyeyu/network/FileRequest.java

@@ -43,19 +43,19 @@ public class FileRequest extends JacksonRequest {
 
 	@Override
 	public FileRequest header(String key, String value) {
-		request.addHeader(key, value);
+		super.header(key, value);
 		return this;
 	}
 
 	@Override
 	public FileRequest token(String token) {
-		request.addHeader("Token", token);
+		super.token(token);
 		return this;
 	}
 
 	@Override
 	public FileRequest language(String langHeader) {
-		request.addHeader("Accept-Language", langHeader);
+		super.language(langHeader);
 		return this;
 	}