What is the right approach to lazy load an attribute without using byte-code enhancement?
There is none. It’s simply not possible. The only things that can be lazy loaded without bytecode enhancement are associations and that works by creating proxies.
@beikov Is it possible to enable byte-code enhancement for selective classes? Also, it is possible to enable byte-code enhancement at application run-time?
You could enhance just certain classes with the build time enhancement plugin by splitting your persistence model into different JARs/projects and applying the enhancer only on the JARs that you want to enhance, but if you want to use runtime enhancement, you can only enhance everything.
You can read more about runtime enhancement in the documentation.