public Section getSection(String sectionName) {
        String name = cleanName(sectionName);
        return sections.get(name);
    }
Returns the {@link Section} with the given name or {@code null} if no section with that name exists.

@param sectionName the name of the section to retrieve.
@return the {@link Section} with the given name or {@code null} if no section with that name exists.
config/core/src/main/java/org/apache/shiro/config/Ini.java