better JavaHOW

## file FooAttrTest.pl
use v6;

use Foo:from<Java>;

Foo.HOW.add_method(Foo, "baz", method ($self:) {
    Proxy.new:
        FETCH => method () { $self."field/get_baz/I"() },
        STORE => method ($new_val)  { $self."field/set_baz/I"($new_val) };
});

my $foo = Foo.new;

# .say for sort $foo.^methods;

say "hi";
say $foo.baz;
say "hi";
$foo.baz = 10;
say $foo.baz;

#`[[
public class Foo {
    public int baz;

    public Foo() {
        baz = 5;
    }
}
]]

## output
$ CLASSPATH=$PWD ./perl6-j FooAttrTest.pl 
hi
5
hi
10