Instead of the method parameter use an additional local variable with the same value assigned; i.e. instead of:
public void observe(@Observes @Juicy String payload) {
Arrays.asList( "foo" ).stream().filter((s) -> s.equals(payload));
}
use this:
public void observe(@Observes @Juicy String payload) {
String p = payload;
Arrays.asList( "foo" ).stream().filter((s) -> s.equals(p));
}