> Java provides inheritance and interfaces, but it doesn’t provide first-class delegation or traits.

I'm not sure I am missing first class delegation much (not a lot of UI projects in Java these days).

But interfaces with default (and static) method implementations are actually quite usable as traits / mixins. Since Java 8 IIRC.

You can also pass around functions / lambdas (coincidentally also since Java 8) to compose functionality together. A bit harder to follow and/or understand, but another perfectly legitimate and very powerful tool nevertheless.