private static boolean isGuardClause(PsiStatement statement) {
    if (!(statement instanceof PsiIfStatement ifStatement)) {
      return false;
    }
    if (ifStatement.getElseBranch() != null) {
      return false;
    }
    final PsiStatement thenBranch = ifStatement.getThenBranch();
    if (thenBranch instanceof PsiReturnStatement) {
      return true;
    }
    if (!(thenBranch instanceof PsiBlockStatement blockStatement)) {
      return false;
    }
    final PsiCodeBlock codeBlock = blockStatement.getCodeBlock();
    final PsiStatement containedStatement = ControlFlowUtils.getOnlyStatementInBlock(codeBlock);
    return containedStatement instanceof PsiReturnStatement;
  }
private static boolean isGuardClause(PsiStatement statement)