How a particular field is filtered from reflection access?

How Java restrict reflection access to the field private final ClassLoader classLoader in Class.java? (As shown in documentation in screenshot)

I have found a link which describes that a SecurityManager can be used to restrict reflection access but how can I use that. Please explain in detail.

And after that I want to restrict access only to a particular field.

Found similar question but want to know how can I implement this in my class and as already asked in the question why this is implemented in jdk? Can I also break this chain using reflection?

It's protected by the JVM by special mechanisms not available to you. Even if you have all the permissions, you can't access it through reflection although normally private fields could be made accessible.

For us mortals, the best we can do is use a SecurityManager that prevents reflection access, and more importantly design our software so it doesn't rely on Java to keep things secret.

To answer your edit, since I was apparently unclear(?)

"how can I implement this in my class?" You can't.

"why this is implemented in jdk?" So you can't use reflection to bypass it.

"Can I also break this chain using reflection?" No, that's the whole point.