Example for unmaintainable-code-22 https://medium.com/@akaita/30-rules-to-make-your-code-unmaintainable-7e5dbafd5bce

unmaintainable-code-22.java

if ( function_A() == OK )
    {
    if ( function_B() == OK )
        {
        /* Normal completion stuff */
        }
    else
        {
        /* some error recovery for Function_B */
        }
    }
    else
        {
        /* some error recovery for Function_A */
        }