Using package resizegather leads to extra vertical space inside mdframed equations

Question

When I try to add package resizegather, extra vertical space is added into mdframed equations. By gradually truncating the code, I found that commenting package resizegather would fix the problem. See figure below. But I have no idea, what is behind that. I found similar issues described in tasks:

• mdframed package + align gives extra vertical space
• Extra vertical space inside mdframed theorem environment

but it didn't help

MNWE:

\documentclass{scrbook}

\usepackage{mdframed}
\usepackage{amsmath}
\usepackage{resizegather}    
\usepackage{blindtext}

\begin{document}
  \chapter{My title test 7}
    \blindtext  
    \begin{mdframed}
      \begin{equation}\label{mai:eq1}
        \boxed{\int f(x) dx = F(x) + c}
      \end{equation}
    \end{mdframed}
    \blindtext  
\end{document}

Answer 1

You can solve the problem with nccmath and its \useshortskip command:

\documentclass{scrbook}

\usepackage{mdframed}
\usepackage{amsmath, nccmath}
\usepackage{resizegather}
\usepackage{blindtext}

\begin{document}
  \chapter{My title test 7}
    \blindtext
    \begin{mdframed}\useshortskip
      \begin{equation}\label{mai:eq1}
        \boxed{\int f(x) dx = F(x) + c}
      \end{equation}
    \end{mdframed}
    \blindtext
\end{document}