I've already shown that type hints do not constitute type checking:

  (defn f [^String s] (.length s))
  (f 3)

is a valid Clojure program that fails at runtime with a cast error.

  class X { public static int f(String s) { return s.length(); } }
  X.f(3)

is not a valid Java program at all. Clojure compilation generates bytecode to dispatch dynamically and all but the most basic checks are handled at runtime by the JVM. This is fundamentally different to the static type checking that languages like Java and Scala do. It's not that Clojure is hiding something from Java, but rather that it isn't doing the considerable amount of effort the Java type checker does to analyse the program before execution. This is by design - Clojure has deliberately avoided adding a static type system in favour of things like spec.