Need help to adding helper or drop down blocks in extension

[Taifun]

here is an example which I used for my battery manager extension App Inventor Extensions: Battery Manager | Pura Vida Apps

one of the helper classes looks like that (here for the Health helper blocks)

package com.puravidaapps.TaifunBattery.helpers;

import java.util.HashMap;
import java.util.Map;
import com.google.appinventor.components.common.OptionList;



/**
 * Defines a Health type
 */

public enum Health implements OptionList<String> {
  Cold("cold"),
  Dead("dead"),
  Good("good"),
  Overheat("overheat"),
  OverVoltage("over voltage"),
  Unknown("unknown"),
  UnspecifiedFailure("unspedified failure");


  private String health;

  Health(String h) {
    this.health = h;
  }


  public String toUnderlyingValue() {
    return health;
  }

  private static final Map<String, Health> lookup = new HashMap<>();

  static {
    for(Health h : Health.values()) {
      lookup.put(h.toUnderlyingValue(), h);
    }
  }

  public static Health fromUnderlyingValue(String h) {
    return lookup.get(h);
  }


}

in the main class I just added

import com.puravidaapps.TaifunBattery.helpers.*;

Taifun