Move proxy configuration form out of pluginManager screens as it is not related

core/src/main/java/hudson/PluginManager.java

@@ -1803,13 +1803,7 @@
         jenkins.checkPermission(Jenkins.ADMINISTER);
 
         ProxyConfiguration pc = req.bindJSON(ProxyConfiguration.class, req.getSubmittedForm());
-        if (pc.name == null) {
-            jenkins.proxy = null;
-            ProxyConfiguration.getXmlFile().delete();
-        } else {
-            jenkins.proxy = pc;
-            jenkins.proxy.save();
-        }
+        ProxyConfigurationManager.saveProxyConfiguration(pc);
         return new HttpRedirect("advanced");
     }
 

core/src/main/java/hudson/ProxyConfigurationManager.java

@@ -0,0 +1,72 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2023, CloudBees Inc, and other contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package hudson;
+
+import edu.umd.cs.findbugs.annotations.NonNull;
+import hudson.model.Descriptor;
+import java.io.IOException;
+import jenkins.model.GlobalConfiguration;
+import jenkins.model.Jenkins;
+import net.sf.json.JSONObject;
+import org.kohsuke.accmod.Restricted;
+import org.kohsuke.accmod.restrictions.NoExternalUse;
+import org.kohsuke.stapler.StaplerRequest;
+
+@Extension @Restricted(NoExternalUse.class)
+public class ProxyConfigurationManager extends GlobalConfiguration {
+
+    @NonNull
+    @Override
+    public String getDisplayName() {
+        return Messages.ProxyConfigurationManager_DisplayName();
+    }
+
+    public Descriptor<ProxyConfiguration> getProxyDescriptor() {
+        return Jenkins.get().getDescriptor(ProxyConfiguration.class);
+    }
+
+    @Override
+    public boolean configure(StaplerRequest req, JSONObject json) throws FormException {
+        ProxyConfiguration pc = req.bindJSON(ProxyConfiguration.class, json);
+        try {
+            saveProxyConfiguration(pc);
+        } catch (IOException e) {
+            throw new FormException(e.getMessage(), e, null);
+        }
+        return true;
+    }
+
+    public static void saveProxyConfiguration(ProxyConfiguration pc) throws IOException {
+        Jenkins jenkins = Jenkins.get();
+        if (pc.name == null) {
+            jenkins.proxy = null;
+            ProxyConfiguration.getXmlFile().delete();
+        } else {
+            jenkins.proxy = pc;
+            jenkins.proxy.save();
+        }
+    }
+
+}

core/src/main/resources/hudson/Messages.properties

@@ -127,3 +127,5 @@ PluginWrapper.NoSuchPlugin=No such plugin found with the name ''{0}''
 PluginWrapper.Error.Disabling=There was an error disabling the ''{0}'' plugin. Error: ''{1}''
 TcpSlaveAgentListener.PingAgentProtocol.displayName=Ping protocol
 
+ProxyConfigurationManager.DisplayName=Proxy Configuration
+ProxyConfigurationManager.Description=Configure the http proxy used by Jenkins

core/src/main/resources/hudson/PluginManager/advanced.jelly

@@ -37,22 +37,11 @@ THE SOFTWARE.
         <l:main-panel>
           <l:app-bar title="${%Advanced settings}"/>
 
+          <div class="alert alert-info">
+              <strong>${%The Proxy configuration form has been moved to} <a href="${rootURL}/manage/configure">Configure System page</a></strong>
+          </div>
+
           <div class="jenkins-form">
-            <section class="jenkins-section jenkins-!-margin-bottom-5">
-                <h2 class="jenkins-section__title">${%HTTP Proxy Configuration}</h2>
-                <f:form method="post" action="proxyConfigure" name="proxyConfigure">
-                    <j:scope>
-                        <j:set var="instance" value="${app.proxy}"/>
-                        <j:set var="descriptor" value="${it.proxyDescriptor}"/>
-                        <st:include from="${descriptor}" page="${descriptor.configPage}"/>
-                    </j:scope>
-                    <l:isAdmin>
-                        <f:block>
-                            <f:submit/>
-                        </f:block>
-                    </l:isAdmin>
-                </f:form>
-            </section>
 
             <l:isAdmin>
                 <section class="jenkins-section jenkins-!-margin-bottom-5">

core/src/main/resources/hudson/ProxyConfigurationManager/config.jelly

@@ -0,0 +1,35 @@
+<!--
+The MIT License
+
+Copyright (c) 2023, CloudBees Inc, and other contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+-->
+
+<?jelly escape-by-default='true'?>
+<j:jelly xmlns:j="jelly:core" xmlns:st="jelly:stapler" xmlns:d="jelly:define" xmlns:l="/lib/layout"
+         xmlns:t="/lib/hudson" xmlns:f="/lib/form">
+    <f:section title="${%HTTP Proxy Configuration}">
+        <j:scope>
+            <j:set var="descriptor" value="${instance.getProxyDescriptor()}"/>
+            <j:set var="instance" value="${app.proxy}"/>
+            <st:include from="${descriptor}" page="${descriptor.configPage}"/>
+        </j:scope>
+    </f:section>
+</j:jelly>