Test with Java 17 (#98)

Jenkinsfile

@@ -5,12 +5,12 @@
 buildPlugin(useContainerAgent: true, configurations: [
   // Test the long-term support end of the compatibility spectrum (i.e., the minimum required
   // Jenkins version).
-  [ platform: 'linux', jdk: '8', jenkins: null ],
+  [ platform: 'linux', jdk: '8' ],
 
   // Test the common case (i.e., a recent LTS release) on both Linux and Windows.
-  [ platform: 'linux', jdk: '8', jenkins: '2.303.2' ],
-  [ platform: 'windows', jdk: '8', jenkins: '2.303.2' ],
+  [ platform: 'linux', jdk: '11', jenkins: '2.332.1' ],
+  [ platform: 'windows', jdk: '11', jenkins: '2.332.1' ],
 
   // Test the bleeding edge of the compatibility spectrum (i.e., the latest supported Java runtime).
-  [ platform: 'linux', jdk: '11', jenkins: '2.303.2' ],
+  [ platform: 'linux', jdk: '17', jenkins: '2.342' ],
 ])

pom.xml

@@ -27,7 +27,7 @@ THE SOFTWARE.
 	<parent>
 		<groupId>org.jenkins-ci.plugins</groupId>
 		<artifactId>plugin</artifactId>
-		<version>4.39</version>
+		<version>4.40</version>
 		<relativePath />
 	</parent>
 
@@ -52,7 +52,6 @@ THE SOFTWARE.
 		<changelist>-SNAPSHOT</changelist>
 		<gitHubRepo>jenkinsci/http-request-plugin</gitHubRepo>
 		<jenkins.version>2.249.1</jenkins.version>
-		<java.level>8</java.level>
 		<hpi.compatibleSinceVersion>1.8.17</hpi.compatibleSinceVersion>
 	</properties>