DataSource.java

    
public Observable<String> getPokemonAbilityStringObservable(String id) {
        return pokemonService.getPokemon(id)
                .map(new Function<Pokemon, String>() {
                    @Override
                    public String apply(@NonNull Pokemon pokemon) throws Exception {
                        return constructAbility(pokemon);
                    }
                });
    }

    private static String constructAbility(Pokemon pokemon) {
        StringBuilder builder = new StringBuilder();
        builder.append(constructPokemon(pokemon));
        for (Pokemon.Ability ability : pokemon.getAbilities()) {
            builder.append("Ability Name : ")
                    .append(ability.getAbility().getName())
                    .append("\n Is Hidden : ")
                    .append(ability.getIsHidden());
        }
        return builder.toString();
    }