private static PsiReferenceExpression extractVariableReference(PsiBinaryExpression expression) {
      final PsiExpression lhs = PsiUtil.skipParenthesizedExprDown(expression.getLOperand());
      if (lhs == null) {
        return null;
      }
      final PsiExpression rhs = PsiUtil.skipParenthesizedExprDown(expression.getROperand());
      if (rhs == null) {
        return null;
      }
      if (PsiTypes.nullType().equals(rhs.getType())) {
        if (!(lhs instanceof PsiReferenceExpression)) {
          return null;
        }
        return (PsiReferenceExpression)lhs;
      }
      if (PsiTypes.nullType().equals(lhs.getType())) {
        if (!(rhs instanceof PsiReferenceExpression)) {
          return null;
        }
        return (PsiReferenceExpression)rhs;
      }
      return null;
    }
private static PsiReferenceExpression extractVariableReference(PsiBinaryExpression expression)