Goal

Define converters (static method or not) then be able to use them for single object or collections through ObjectConverter interface.

Example

public static class LenConverter {
    // static method
    
    @Converter(in = In.class, out = Out.class)
    public static Out convert(final In in) {
        return new Out(in.value.length());
    }

    // or use completely CDI

    @Inject
    private Helper helper;

    @Converter(in = String.class, out = String.class)
    public String convert(final String in) {
        return helper.foo(in);
    }
}

then in another bean:

@Inject
@Converter(in = In.class, out = Out.class)
private ObjectConverter<In, Out> len;

// ...
assertEquals(3, len.to(new In("foo")).len);