code: @SuppressWarnings({"unused", "WeakerAccess"})
      public void addMultiValuesForKey(final String key, final ArrayList<String> values) {
          postAsyncSafely("addMultiValuesForKey", new Runnable() {
              @Override
              public void run() {
                  final String command = (getLocalDataStore().getProfileValueForKey(key) != null) ? Constants.COMMAND_ADD : Constants.COMMAND_SET;
                  _handleMultiValues(values, key, command);
              }
          });
      }
docs: Add a collection of unique values to a multi-value user profile property
  If the property does not exist it will be created
  <p/>
  Max 100 values, on reaching 100 cap, oldest value(s) will be removed.
  Values must be Strings and are limited to 512 characters.
  <p/>
  If the key currently contains a scalar value, the key will be promoted to a multi-value property
  with the current value cast to a string and the new value(s) added
  
  @param key    String
  @param values {@link ArrayList} with String values