GH-483 JDK 20-ea support added

Author: thurka

plugins/jfr.streaming/manifest.mf

@@ -4,4 +4,4 @@ OpenIDE-Module: org.graalvm.visualvm.jfr.streaming
 OpenIDE-Module-Install: org/graalvm/visualvm/jfr/streaming/Installer.class
 OpenIDE-Module-Java-Dependencies: Java > 17
 OpenIDE-Module-Localizing-Bundle: org/graalvm/visualvm/jfr/streaming/Bundle.properties
-OpenIDE-Module-Specification-Version: 1.1
+OpenIDE-Module-Specification-Version: 1.2

plugins/jfr.streaming/src/org/graalvm/visualvm/jfr/streaming/JFRStream.java

@@ -50,7 +50,7 @@ public class JFRStream {
     public static JFRStream getFor(Application app) throws IOException {
         Jvm jvm = JvmFactory.getJVMFor(app);
         String ver = jvm.getJavaVersion();
-        if (isJavaVersion(ver, "17") || isJavaVersion(ver, "18") || isJavaVersion(ver, "19")) {
+        if (isJavaVersion(ver, "17") || isJavaVersion(ver, "18") || isJavaVersion(ver, "19") || isJavaVersion(ver, "20")) {
             JmxModel jmxModel = JmxModelFactory.getJmxModelFor(app);
             if (jmxModel != null && jmxModel.getConnectionState() == JmxModel.ConnectionState.CONNECTED) {
                 return new JFRStream(jmxModel);