With a colleague, we discuss about the fact that function type can or not obfuscate Java code and he advocate the fact that a code in Java is always readable if you have an IDE that can auto-format the code.
The following example doesn't answer to the question about function type but shows that it is always possible to write an obfuscated code even in Java. This example is extracted from the BlueJ mailing list.

/*   Just Java
     Peter van der Linden
     April 1, 1996.

\u0050\u0076\u0064\u004c\u0020\u0031\u0020\u0041\u0070\u0072\u0039\u0036
 \u002a\u002f\u0020\u0063\u006c\u0061\u0073\u0073\u0020\u0068\u0020\u007b
  \u0020\u0020\u0070\u0075\u0062\u006c\u0069\u0063\u0020\u0020\u0020\u0020
   \u0073\u0074\u0061\u0074\u0069\u0063\u0020\u0020\u0076\u006f\u0069\u0064
    \u006d\u0061\u0069\u006e\u0028\u0020\u0053\u0074\u0072\u0069\u006e\u0067
     \u005b\u005d\u0061\u0029\u0020\u007b\u0053\u0079\u0073\u0074\u0065\u006d
      \u002e\u006f\u0075\u0074\u002e\u0070\u0072\u0069\u006e\u0074\u006c\u006e
       \u0028\u0022\u0048\u0069\u0021\u0022\u0029\u003b\u007d\u007d\u002f\u002a

 */

For those that have problems with reading unicode characters encoded in hexa :)
It's equivalent to

class h {
  public static void main(String[] args) {
    System.out.println("Hi!");
  }
}

Rémi Forax