Use symbol instead of PNG file

pom.xml

@@ -45,7 +45,8 @@
   <properties>
     <changelist>999999-SNAPSHOT</changelist>
     <gitHubRepo>jenkinsci/${project.artifactId}-plugin</gitHubRepo>
-    <jenkins.baseline>2.479.3</jenkins.baseline>
+    <jenkins.baseline>2.479</jenkins.baseline>
+    <jenkins.version>${jenkins.baseline}.3</jenkins.version>
   </properties>
 
   <licenses>
@@ -63,6 +64,25 @@
     <tag>${scmTag}</tag>
   </scm>
 
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>io.jenkins.tools.bom</groupId>
+        <artifactId>bom-${jenkins.baseline}.x</artifactId>
+        <version>4669.v0e99c712a_30e</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+
+  <dependencies>
+    <dependency>
+      <groupId>io.jenkins.plugins</groupId>
+      <artifactId>ionicons-api</artifactId>
+    </dependency>
+  </dependencies>
+
   <!-- get every artifact through repo.jenkins-ci.org, which proxies all the artifacts that we need -->
   <repositories>
     <repository>

src/main/java/com/cloudbees/simplediskusage/QuickDiskUsageManagementLink.java

@@ -23,6 +23,7 @@
  */
 package com.cloudbees.simplediskusage;
 
+import edu.umd.cs.findbugs.annotations.NonNull;
 import hudson.Extension;
 import hudson.model.ManagementLink;
 import hudson.security.Permission;
@@ -33,40 +34,33 @@
 public class QuickDiskUsageManagementLink extends ManagementLink implements StaplerProxy {
     @Override
     public String getIconFileName() {
-        return "/plugin/cloudbees-disk-usage-simple/images/disk.png";
+        return "symbol-pie-chart-outline plugin-ionicons-api";
     }
 
     @Override
     public String getDescription() {
         return "Simple disk usage estimation";
     }
 
     @Override
     public String getDisplayName() {
         return "Disk usage";
     }
 
     @Override
     public String getUrlName() {
         return "disk-usage-simple";
     }
 
     @Override
     public Permission getRequiredPermission() {
         return Jenkins.SYSTEM_READ;
     }
 
-    /**
-     * Name of the category for this management link. Exists so that plugins with core dependency pre-dating the version
-     * when this was introduced can define a category.
-     *
-     * TODO when the core version is >2.226 change this to override {@code getCategory()} instead
-     *
-     * @return name of the desired category, one of the enum values of Category, e.g. {@code STATUS}.
-     * @since 2.226 of Jenkins core
-     */
-    public String getCategoryName() {
-        return "STATUS";
+    @NonNull
+    @Override
+    public Category getCategory() {
+        return Category.STATUS;
     }
 
     /**

src/main/resources/com/cloudbees/simplediskusage/QuickDiskUsagePlugin/sidepanel.jelly

@@ -33,10 +33,10 @@
     <l:tasks>
       <l:task href="${rootURL}/" icon="icon-up icon-md" title="${%Back to Dashboard}"/>
       <l:task href="${rootURL}/manage" icon="icon-setting icon-md" title="${%Manage Jenkins}"/>
-      <l:task href="." icon="/plugin/cloudbees-disk-usage-simple/images/disk.png" title="${%Disk usage}"/>
+      <l:task href="." icon="symbol-pie-chart-outline plugin-ionicons-api" title="${%Disk usage}"/>
       <j:if test="${not it.running}">
         <st:adjunct includes="com.cloudbees.simplediskusage.QuickDiskUsagePlugin.refresh-disk-usage"/>
-        <l:task href="." data-callback="refreshDiskUsage" icon="icon-refresh icon-md" title="${%Refresh disk usage}" post="true"/>
+        <l:task href="." data-callback="refreshDiskUsage" icon="symbol-refresh icon-md" title="${%Refresh disk usage}" post="true"/>
       </j:if>
     </l:tasks>
   </l:side-panel>