Write-only in this context means that the cost of maintaining something vastly exceeds the cost of rewriting that something from scratch. I don't know Spring a

Write-only in this context means that the cost of maintaining something vastly exceeds the cost of rewriting that something from scratch. I don't know Spring and Spring Boot well enough to pass judgement, but this situation generally arises in software when you have a language or framework that's reasonably expressive, where the language has a lot of sigils or keywords and it has "shortcuts" that you have to grok before you can really understand codebases that use those shortcuts (like annotations or heavy/excessive use of design patterns). It leads to software solutions that are only well understood by the original authors due to their specific knowledge and problem solving approach and anyone who comes along later must have the exact same overlap of knowledge and skills otherwise they'll find it easier to start fresh. This includes the original authors if the time lapse has been long enough. This often then leads to the next phase of miserable software jobs, the second-system effect.