Use ionicon instead of custom image in side panel

pom.xml

@@ -118,6 +118,10 @@
         </build>
 
 	<dependencies>
+		<dependency>
+			<groupId>io.jenkins.plugins</groupId>
+			<artifactId>ionicons-api</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.jenkins-ci.plugins</groupId>
 			<artifactId>matrix-project</artifactId>

src/main/java/jenkins/advancedqueue/PriorityConfiguration.java

@@ -64,6 +64,7 @@
 
 import org.acegisecurity.context.SecurityContext;
 import org.acegisecurity.context.SecurityContextHolder;
+import org.jenkins.ui.icon.IconSpec;
 import org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution;
 import org.kohsuke.stapler.QueryParameter;
 import org.kohsuke.stapler.StaplerRequest;
@@ -74,7 +75,7 @@
  * @since 2.0
  */
 @Extension
-public class PriorityConfiguration extends Descriptor<PriorityConfiguration> implements RootAction, Describable<PriorityConfiguration> {
+public class PriorityConfiguration extends Descriptor<PriorityConfiguration> implements RootAction, IconSpec, Describable<PriorityConfiguration> {
 
 	private final static Logger LOGGER = Logger.getLogger(PriorityConfiguration.class.getName());
 
@@ -104,11 +105,18 @@ public PriorityConfiguration() {
 		}
 	}
 
+	@Override
 	public String getIconFileName() {
+		return null;
+	}
+
+	@Override
+	public String getIconClassName() {
 		if (!checkActive()) {
 			return null;
 		}
-		return "/plugin/PrioritySorter/advqueue.svg";
+
+		return "symbol-swap-vertical-outline plugin-ionicons-api";
 	}
 
 	@Override