Switch to new parent pom, https://github.com/jenkinsci/plugin-pom

pom.xml

@@ -3,9 +3,15 @@
     <parent>
         <groupId>org.jenkins-ci.plugins</groupId>
         <artifactId>plugin</artifactId>
-        <version>1.609</version>
+        <version>2.3</version>
     </parent>
 
+    <properties>
+      <jenkins.version>1.609.1</jenkins.version>
+      <hpi-plugin.version>1.115</hpi-plugin.version>
+      <jenkins-test-harness.version>${jenkins.version}</jenkins-test-harness.version>
+    </properties>
+
   <artifactId>gitlab-plugin</artifactId>
   <version>1.1.30-SNAPSHOT</version>
   <name>GitLab Plugin</name>

src/main/resources/com/dabsquared/gitlabjenkins/GitLabPushTrigger/config.jelly

@@ -1,3 +1,4 @@
+<?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">
 

src/main/resources/com/dabsquared/gitlabjenkins/GitLabPushTrigger/global.jelly

@@ -1,3 +1,4 @@
+<?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="Gitlab">
     <f:entry title="Gitlab host URL" field="gitlabHostUrl"

src/main/resources/com/dabsquared/gitlabjenkins/GitLabPushTrigger/help.jelly

@@ -1,3 +1,4 @@
+<?jelly escape-by-default='true'?>
 <div>
     Configure GitLab to deliver a POST request to your Jenkins instance like GitLab CI.
 </div>

src/main/resources/index.jelly

@@ -1,3 +1,4 @@
+<?jelly escape-by-default='true'?>
 <div>
     This plugin integrates <a href="http://gitlab.com/">GitLab</a> to Jenkins by faking a GitLab CI Server.
 </div>