private static String cleanName(String sectionName) {
        String name = StringUtils.clean(sectionName);
        if (name == null) {
            LOGGER.trace("Specified name was null or empty.  Defaulting to the default section (name = \"\")");
            name = DEFAULT_SECTION_NAME;
        }
        return name;
    }
Removes the section with the specified name and returns it, or {@code null} if the section did not exist.

@param sectionName the name of the section to remove.
@return the section with the specified name or {@code null} if the section did not exist.
config/core/src/main/java/org/apache/shiro/config/Ini.java