Maven

<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>bootstrap</artifactId>
    <version>4.5.0</version>
</dependency>
<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>jquery</artifactId>
    <version>3.5.1</version>
</dependency>
<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>font-awesome</artifactId>
    <version>5.13.0</version>
</dependency>
<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>animate.css</artifactId>
    <version>3.5.2</version>
</dependency>

<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>select2</artifactId>
    <version>4.0.13</version>
</dependency>

Thymeleaf

<link rel="stylesheet" type="text/css" th:href="@{/webjars/bootstrap/4.5.0/css/bootstrap.min.css}" />
<link rel="stylesheet" type="text/css" th:href="@{/webjars/font-awesome/5.13.0/css/all.min.css}" />
<link rel="stylesheet" type="text/css" th:href="@{/webjars/animate.css/3.5.2/animate.min.css}" />
<link rel="stylesheet" type="text/css" th:href="@{/css/main.css}" />

<script type="text/javascript" th:src="@{/webjars/jquery/3.5.1/jquery.min.js}"></script>
<script type="text/javascript" th:src="@{/webjars/bootstrap/4.5.0/js/bootstrap.min.js}"></script>