Added Java Version to the metrics

connector/src/main/java/org/geysermc/connector/GeyserConnector.java

@@ -81,6 +81,8 @@ import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 @Getter
 public class GeyserConnector {
@@ -330,6 +332,40 @@ public class GeyserConnector {
                     return versionMap;
                 }));
             }
+
+            // The following code can be attributed to the PaperMC project
+            // https://github.com/PaperMC/Paper/blob/master/Spigot-Server-Patches/0005-Paper-Metrics.patch#L614
+            metrics.addCustomChart(new Metrics.DrilldownPie("javaVersion", () -> {
+                Map<String, Map<String, Integer>> map = new HashMap<>();
+                String javaVersion = System.getProperty("java.version");
+                Map<String, Integer> entry = new HashMap<>();
+                entry.put(javaVersion, 1);
+
+                // http://openjdk.java.net/jeps/223
+                // Java decided to change their versioning scheme and in doing so modified the
+                // java.version system property to return $major[.$minor][.$security][-ea], as opposed to
+                // 1.$major.0_$identifier we can handle pre-9 by checking if the "major" is equal to "1",
+                // otherwise, 9+
+                String majorVersion = javaVersion.split("\\.")[0];
+                String release;
+
+                int indexOf = javaVersion.lastIndexOf('.');
+
+                if (majorVersion.equals("1")) {
+                    release = "Java " + javaVersion.substring(0, indexOf);
+                } else {
+                    // of course, it really wouldn't be all that simple if they didn't add a quirk, now
+                    // would it valid strings for the major may potentially include values such as -ea to
+                    // denote a pre release
+                    Matcher versionMatcher = Pattern.compile("\\d+").matcher(majorVersion);
+                    if (versionMatcher.find()) {
+                        majorVersion = versionMatcher.group(0);
+                    }
+                    release = "Java " + majorVersion;
+                }
+                map.put(release, entry);
+                return map;
+            }));
         }
 
         boolean isGui = false;

connector/src/main/java/org/geysermc/connector/metrics/Metrics.java

@@ -152,20 +152,15 @@ public class Metrics {
      */
     private ObjectNode getServerData() {
         // OS specific data
-        int playerAmount = connector.getPlayers().size();
-
         String osName = System.getProperty("os.name");
         String osArch = System.getProperty("os.arch");
         String osVersion = System.getProperty("os.version");
-        String javaVersion = System.getProperty("java.version");
         int coreCount = Runtime.getRuntime().availableProcessors();
 
         ObjectNode data = mapper.createObjectNode();
 
         data.put("serverUUID", serverUUID);
 
-        data.put("playerAmount", playerAmount);
-        data.put("javaVersion", javaVersion);
         data.put("osName", osName);
         data.put("osArch", osArch);
         data.put("osVersion", osVersion);