Enable Spotless for automatic formatting (#421)

pom.xml

@@ -78,6 +78,9 @@
     -->
     <spotbugs.omitVisitors>FindReturnRef</spotbugs.omitVisitors>
 
+    <!-- Set to false to enable Spotless -->
+    <spotless.check.skip>true</spotless.check.skip>
+
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <project.build.outputEncoding>UTF-8</project.build.outputEncoding>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
@@ -119,6 +122,7 @@
     <mockito.version>5.3.0</mockito.version>
     <spotbugs-annotations.version>4.7.3</spotbugs-annotations.version>
     <spotbugs-maven-plugin.version>4.7.3.4</spotbugs-maven-plugin.version>
+    <spotless-maven-plugin.version>2.36.0</spotless-maven-plugin.version>
     <stapler-plugin.version>1.23</stapler-plugin.version>
   </properties>
 
@@ -195,6 +199,11 @@
           <artifactId>maven-license-plugin</artifactId>
           <version>${maven-license-plugin.version}</version>
         </plugin>
+        <plugin>
+          <groupId>com.diffplug.spotless</groupId>
+          <artifactId>spotless-maven-plugin</artifactId>
+          <version>${spotless-maven-plugin.version}</version>
+        </plugin>
         <plugin>
           <groupId>com.github.spotbugs</groupId>
           <artifactId>spotbugs-maven-plugin</artifactId>
@@ -602,6 +611,37 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>com.diffplug.spotless</groupId>
+        <artifactId>spotless-maven-plugin</artifactId>
+        <configuration>
+          <java>
+            <endWithNewline />
+            <importOrder />
+            <indent>
+              <spaces>true</spaces>
+            </indent>
+            <palantirJavaFormat />
+            <removeUnusedImports />
+            <trimTrailingWhitespace />
+          </java>
+          <pom>
+            <sortPom>
+              <expandEmptyElements>false</expandEmptyElements>
+              <sortDependencies>scope,groupId,artifactId</sortDependencies>
+              <sortDependencyExclusions>groupId,artifactId</sortDependencyExclusions>
+              <spaceBeforeCloseEmptyElement>true</spaceBeforeCloseEmptyElement>
+            </sortPom>
+          </pom>
+        </configuration>
+        <executions>
+          <execution>
+            <goals>
+              <goal>check</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
 
       <plugin>
         <artifactId>maven-enforcer-plugin</artifactId>