Java's implementation of generics was heavily influenced by a language called Pizza. Sun hired the author of the language, Martin Odersky, to write the compiler

Java's implementation of generics was heavily influenced by a language called Pizza. Sun hired the author of the language, Martin Odersky, to write the compiler for Java. Odersky later went on to develop Scala. Java improving borrowing ideas from other JVM languages had happened in the past, and that has made the ecosystem stronger. Nothing unfortunate about it.