Re: "Even if something has been written in Java in 90s that is still 20 years ago."
Yes, Things Change.
A brilliant example of this is RBS/NatWest Telephone, Online and Mobile banking.
A telephone banking system was developed to hook into the main banking system. This telephone banking system is separate to the main branch system, logging all transactions against a four digit call number, before passing them over to the main banking system.
Becauase parts of the main branch banking system dates back to the 60s, it was not possible to actually integrate the telephone banking system fully; it has to sit separately and just pass transaction messages back and forth as if it were a special type of branch terminal.
The online banking system was developed to hang off the end of the telephone banking system, so all transactions are passed to the telephone banking system and treated as coming from a telephone "call", before being transferred to the main branch system with a call number.
The mobile banking system hangs off the end of both the online and telephone banking systems, but cannot generate proper call numbers, so simply logs everything against telephone call 0, then leaves the telephone banking system to pass the transaction over to the branch system.
So, a right mess there then, with lots of potential to go wrong. No decent software engineer would even consider designing a system that way if implemented today - the potential for failures and security flaws is just too high.
You will also notice how everything is predicated on having a telephone banking login, and how your telephone banking details also double as your online banking log in details, with no easy way to separate the two.