docs: public boolean matches(Attribute<?> other) {
        if (other == null)
           return false;
        if (!this.definition.equals(other.definition))
           return false;
        if (this.definition.isGlobal()) {
           if (Matchable.class.isAssignableFrom(this.definition.getType())) {
              return ((Matchable)value).matches(other.value);
           } else {
              return Objects.equals(value, other.value);
           }
        }
        return true;
     }