replacing toString using Groovy metaprogramming

Question

In the following Groovy snippet, I attempt to replace both the hashCode and toString methods

String.metaClass.toString = {-> "override" }
String.metaClass.hashCode = {-> 22 }

But when I test it out, only the replacement of hashCode works

String s = "foo"
println s.hashCode()  // prints 22
println s.toString()  // prints "foo"

Is toString somehow a special case (possibly for security reasons)?

Answer 1

See the first comment on this issue. It says about String's toString and other String related classes:

(...) seems to be intent, it is probably a good idea to have a faster invocation for classes that don't allow overriding toString().