Modifying final static variable within final public class Java

Question

I have a quick question regarding modifying a final public class. Based on some researches, it seems like final public class cannot be inherited or implemented. My goal is to change one final static variable within this final public class.

class name is: public final class Utils

private static final Set<String> DISALLOWED_HEADERS_SET = Set.of(
    "authorization", "connection", "cookie", "content-length",
    "date", "expect", "from", "host", "origin", "proxy-authorization",
    "referer", "user-agent", "upgrade", "via", "warning");

I want to get rid of authorization field from this DISALLOWED_HEADERS_SET. Is there any ways to doing this?

I heard reflection is one way to modify classes. This is a Apress/java-9-revealed to a github that seems to reveal what's inside of the class

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This thread (question) has been identified as XY problem. I will try to explain with more information on why I want a solution for the above problem. Before digging into the reason that drove me to ask this question, I will cover the current situation of where this problem is at as of now.

It is important to understand that this problem has been already posed by Clevertap to Oracle. If you follow Oracle link, you can see that this problem has been acknowledged and updated to Jdk 11. Hopefully, Oracle applies this fixed source code to the coming Java 10, but it is highly unlikely given the fact that Jdk 9 represents Java 9. This being said, only solution there is to use reflection which the open thread in clevertap suggests.

Now, I will briefly explain what I have achieved and am trying to figure out. I have been working on a framework that I have been developing for sending Push Notification to APNs using Java language. Everything works except one functionality.

[I will share this framework through GitHub in the near future for those trying to send notification to APNs without depending on third party frameworks, such as Jetty, Netty, or okhttp.]

The problem rises when I try to use token as a way of authentication to send notification. I have successfully created token following through the instruction provided by Apple. All I have to do is to set request header with authorization key and bearer <token> value. However, when I use .setHeader derived from jdk9.incubator.httpclient module to set these values, it automatically omits this field. As aforementioned, authorization is part of DISALLOWED_HEADERS_SET and it is clearly not allowed. If a user attempts to set "authorization" as a key value for the request header field, it is deleted. If you have any suggestions to work around this problem. It will be awesome and helpful for others facing the same problem.

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Bad news folks... jdk 9.0.4 removed setSystemHeader method, so if you want to use reflection, you need to use Jdk 9.0.1

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As promised before, I created java library for sending notification using pure java code and pushed it to the github. I used older version that was based on jdk10 for my published app. Older version only supported tls connection. Now the current version based on jdk11 is supporting both tls and token based authentication for sending push notification to APNs.

Answer 1

Will just removing that value from the set work for you? Something like this:

        Field f = Utils.class.getDeclaredField("DISALLOWED_HEADERS_SET");
        f.setAccessible(true);

        @SuppressWarnings("unchecked")
        Set<String> headers = (Set<String>)f.get(null);        
        headers.remove("authorization");