Avoid writing the so-called `PolyNull` or `ParametricNull` methods (where nullability of the result depends on the nullability of the type argument).
One particular example is when a [method returns `null` if and only if its argument is `null`](https://github.com/gradle/gradle/blob/674b8430b024f03cae24f1e4dd6dbaa78b557dae/platforms/core-runtime/base-services/src/main/java/org/gradle/util/internal/TextUtil.java#L163).

ototype.hasOwnProperty),b=D(RegExp.prototype.test),S=(N=TypeError,function(){for(var e=arguments.length,t=new Array(e),n=0;n<e;n++)t[n]=arguments[n];return s(N,t)});var N;function D(e){return function(t){t instanceof RegExp&&(t.lastIndex=0);for(var n=arguments.length,o=new Array(n>1?n-1:0),r=1;r<n;r++)o[r-1]=arguments[r];return c(e,t,o)}}function R(e,o){let r=arguments.length>2&&void 0!==arguments[2]?arguments[2]:h;t&&t(e,null);let i=o.length;for(;i--;){let t=o[i];if("string"==typeof t){const e=...

        PythonJob result = pythonJob.filename("test.py");

        assertSame(pythonJob, result);
        assertEquals("test.py", pythonJob.filename);
    }

    // Test single argument addition
    @Test
    public void test_arg() {
        assertTrue(pythonJob.argList.isEmpty());

        PythonJob result = pythonJob.arg("arg1");

        assertSame(pythonJob, result);

="pending",a={state:function(){return i},always:function(){return s.done(arguments).fail(arguments),this},"catch":function(e){return a.then(null,e)},pipe:function(){var i=arguments;return ce.Deferred(function(r){ce.each(o,function(e,t){var n=v(i[t[4]])&&i[t[4]];s[t[1]](function(){var e=n&&n.apply(this,arguments);e&&v(e.promise)?e.promise().progress(r.notify).done(r.resolve).fail(r.reject):r[t[0]+"With"](this,n?[e]:arguments)})}),i=null}).promise()},then:function(t,n,r){var u=0;function l(i,o,a,s){return...

do
    case $1 in
      --help) ARGV="$ARGV -h"; shift;;
      --*=*) properties="$properties -Dfess.${1#--}"
           shift 1
           ;;
      --*) [ $# -le 1 ] && {
                echo "Option requires an argument: '$1'."
                shift
                continue
            }
           properties="$properties -Dfess.${1#--}=$2"
           shift 2
           ;;
      *) ARGV="$ARGV $1" ; shift
    esac

                case 1:
                    // Success on first call
                    return;
                case 2:
                    throw new IllegalArgumentException("Invalid argument");
                case 3:
                    throw new IllegalStateException("Invalid state");
                case 4:
                    throw new NullPointerException("Null pointer");
                default:

    ;;
    1)
        # Don't do anything on upgrade, because the preun script in redhat gets executed after the postinst (madness!)
    ;;

    *)
        echo "pre remove script called with unknown argument \`$1'" >&2
        exit 1
    ;;
esac

# Stops the service
if [ "$STOP_REQUIRED" = "true" ]; then
    echo -n "Stopping fess service..."
    if command -v systemctl >/dev/null; then

        return null;
    }

    @Override
    public void fetchFirst(int fetchSize) {
        _fetchScopeEffective = true;
        if (fetchSize < 0) {
            String msg = "Argument[fetchSize] should be plus: " + fetchSize;
            throw new IllegalArgumentException(msg);
        }
        _fetchStartIndex = 0;
        _fetchSize = fetchSize;
        _fetchPageNumber = 1;

                    -d "$FESS_USER_HOME"  \
                    "$FESS_USER"
            echo " OK"
        fi
    ;;

    *)
        echo "pre install script called with unknown argument \`$1'" >&2
        exit 1
    ;;
esac

        return null;
    }

    @Override
    public void fetchFirst(int fetchSize) {
        _fetchScopeEffective = true;
        if (fetchSize < 0) {
            String msg = "Argument[fetchSize] should be plus: " + fetchSize;
            throw new IllegalArgumentException(msg);
        }
        _fetchStartIndex = 0;
        _fetchSize = fetchSize;
        _fetchPageNumber = 1;