private static PsiExpression getCheckedExpression(boolean useIsEmpty, PsiExpression expression) {
    if (useIsEmpty || !(expression instanceof PsiMethodCallExpression callExpression)) {
      return expression;
    }
    // to replace stringBuffer.toString().equals("") with
    // stringBuffer.length() == 0
    final PsiReferenceExpression methodExpression = callExpression.getMethodExpression();
    final String referenceName = methodExpression.getReferenceName();
    final PsiExpression qualifierExpression = methodExpression.getQualifierExpression();
    if (qualifierExpression == null) {
      return expression;
    }
    final PsiType type = qualifierExpression.getType();
    if (HardcodedMethodConstants.TO_STRING.equals(referenceName) && type != null && (type.equalsToText(
      CommonClassNames.JAVA_LANG_STRING_BUFFER) || type.equalsToText(CommonClassNames.JAVA_LANG_STRING_BUILDER))) {
      return qualifierExpression;
    }
    else {
      return expression;
    }
  }
private static PsiExpression getCheckedExpression(boolean useIsEmpty, PsiExpression expression)