Java picked these three up over several releases and each looked modest on its own. Together they gave the language something it did not have: exhaustiveness.

Modelling a closed set

Declare a sealed interface, implement it with records, and switch over it. The compiler now knows every shape the type can take and refuses to compile a switch that misses one. Add a case a year later and every switch that needs attention becomes a compile error rather than a production surprise.

• Records give the data carrier without the ceremony.
• Sealed types close the hierarchy so it can be reasoned about.
• Pattern matching destructures without a cast.

This is as close as Java has come to algebraic data types, and it models a domain far better than an enum plus a bag of nullable fields.