code: public void clear() {
          if (mCardNumberEditText.hasFocus()
                  || mExpiryDateEditText.hasFocus()
                  || mCvcNumberEditText.hasFocus()
                  || this.hasFocus()) {
              mCardNumberEditText.requestFocus();
          }
          mCvcNumberEditText.setText("");
          mExpiryDateEditText.setText("");
          mCardNumberEditText.setText("");
      }
docs: Clear all text fields in the CardInputWidget.