NOTE
Netty Source: Bootstrap Creation
How Bootstrap/ServerBootstrap accumulate configuration before channel registration and bind/connect.
This is a historical learning note and may contain outdated or incomplete understanding.
Bootstrap/ServerBootstrap are configuration builders. They collect the event-loop group, channel factory/type, handler(s), channel options, attributes, addresses, and server child configuration.
Creating the bootstrap itself does not open/listen on a socket. Actual channel creation/registration and bind/connect happen later when the corresponding operation is invoked.
This separation explains why a bootstrap can validate configuration before asynchronous I/O begins. Exact validation/helper classes are version-specific.