Pair Wise Swap Linked List

package org.wesome.dsalgo;

import lombok.Data;

import java.util.Objects;

public class LinkedList {
    static Node head;
    static int size = 0;

    static void pairWiseSwap() {
        System.out.println("LinkedList.pairWiseSwap");
        Node temp = head;
        /* Traverse only till there are atleast 2 nodes left */
        while (Objects.nonNull(temp) && Objects.nonNull(temp.next)) {
            /* Swap the data */
            int k = temp.data;
            temp.data = temp.next.data;
            temp.next.data = k;
            temp = temp.next.next;
        }
    }

    static void addInLast(int element) {
        System.out.println("\nLinkedList.addInLast " + element);
        Node newNode = new Node(element);
        if (Objects.isNull(head)) {
            head = newNode;
            return;
        }
        Node tempNode = head;
        while (Objects.nonNull(tempNode.next)) {
            tempNode = tempNode.next;
        }
        tempNode.next = newNode;
        size++;
    }

    //this method print the list using loop
    static void printIteratively() {
        System.out.println("\nLinkedList.printIteratively");
        if (Objects.isNull(head)) {
            System.out.println("Linked List is null = " + head);
            return;
        }
        Node tempNode = head;
        System.out.println("Linked List Size is " + size);
        while (Objects.nonNull(tempNode)) {
            System.out.println("Node = " + tempNode.data);
            tempNode = tempNode.next;
        }
    }
}

@Data
class Node {
    int data;
    Node next;

    public Node(int data) {
        this.data = data;
    }
}

package org.wesome.dsalgo;

import org.junit.jupiter.api.Test;

import static org.wesome.dsalgo.LinkedList.pairWiseSwap;
import static org.wesome.dsalgo.LinkedList.printIteratively;

public class LinkedListTest {
    @Test
    void pairWiseSwapTest() {
        addInLast();
        printIteratively();
        pairWiseSwap();
        printIteratively();
    }

    void addInLast() {
        LinkedList.addInLast(1);
        LinkedList.addInLast(2);
        LinkedList.addInLast(3);
        LinkedList.addInLast(4);
        LinkedList.addInLast(5);
    }
}

plugins {
    id 'java'
    id "io.freefair.lombok" version "6.2.0"
}

group = 'org.wesome'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = JavaVersion.VERSION_1_8

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}

repositories {
    mavenCentral()
}

dependencies {
    testImplementation 'org.junit.jupiter:junit-jupiter:5.6.2'
}

test {
    useJUnitPlatform()
}