Add unreleased version 6.2.4 (#29171)

Author: Christoph Büscher

server/src/main/java/org/elasticsearch/Version.java

@@ -155,6 +155,8 @@ public class Version implements Comparable<Version> {
     public static final Version V_6_2_2 = new Version(V_6_2_2_ID, org.apache.lucene.util.Version.LUCENE_7_2_1);
     public static final int V_6_2_3_ID = 6020399;
     public static final Version V_6_2_3 = new Version(V_6_2_3_ID, org.apache.lucene.util.Version.LUCENE_7_2_1);
+    public static final int V_6_2_4_ID = 6020499;
+    public static final Version V_6_2_4 = new Version(V_6_2_4_ID, org.apache.lucene.util.Version.LUCENE_7_2_1);
     public static final int V_6_3_0_ID = 6030099;
     public static final Version V_6_3_0 = new Version(V_6_3_0_ID, org.apache.lucene.util.Version.LUCENE_7_2_1);
     public static final Version CURRENT = V_6_3_0;
@@ -172,6 +174,8 @@ public static Version fromId(int id) {
         switch (id) {
             case V_6_3_0_ID:
                 return V_6_3_0;
+            case V_6_2_4_ID:
+                return V_6_2_4;
             case V_6_2_3_ID:
                 return V_6_2_3;
             case V_6_2_2_ID: