code: public boolean hasSlotIsTrue(final String slotName) {
          return hasSlot(slotName) && BooleanUtils.toBoolean(intentRequest.getIntent().getSlot(slotName).getValue());
      }
docs: Checks if a slot is contained in the intent request and its value represents a boolean true
  (which could be "on" or "yes" as well)
  @param slotName name of the slot to look after
  @return True, if the slot exists in the intent request and represents a boolean true.