code: @Nullable
    @ReturnsMutableCopy
    public ICommonsList <MimeTypeInfo> getAllInfosOfExtension (@Nullable final String sExtension)
    {
      // Extension may be empty!
      if (sExtension == null)
        return null;
  
      return m_aRWLock.readLocked ( () -> {
        ICommonsList <MimeTypeInfo> ret = m_aMapExt.get (sExtension);
        if (ret == null)
        {
          // Especially on Windows, sometimes file extensions like "JPG" can be
          // found. Therefore also test for the lowercase version of the
          // extension.
          ret = m_aMapExt.get (sExtension.toLowerCase (Locale.US));
        }
        // Create a copy if present
        return ret == null ? null : ret.getClone ();
      });
    }
docs: Get all infos associated with the specified filename extension.
  
  @param sExtension
  The extension to search. May be <code>null</code> or empty.
  @return <code>null</code> if the passed extension is <code>null</code> or
  if no such extension is registered.