code: public final void setHelperText(@Nullable final CharSequence helperText) {
          this.helperText = helperText;
  
          if (getError() == null) {
              setLeftMessage(helperText, null, false);
          }
      }
docs: Sets the helper text, which should be shown, when no validation error is currently shown.
  
  @param helperText
  The helper text, which should be set, as an instance of the type {@link CharSequence}
  or null, if no helper text should be shown