Add unreleased version 6.3.1

Author: dimitris-athanasiou

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

@@ -166,10 +166,10 @@ public class Version implements Comparable<Version>, ToXContentFragment {
     public static final Version V_6_2_3 = new Version(V_6_2_3_ID, 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, LUCENE_7_2_1);
-    public static final int V_6_2_5_ID = 6020599;
-    public static final Version V_6_2_5 = new Version(V_6_2_5_ID, 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_3_1);
+    public static final int V_6_3_1_ID = 6030199;
+    public static final Version V_6_3_1 = new Version(V_6_3_1_ID, org.apache.lucene.util.Version.LUCENE_7_3_1);
     public static final int V_6_4_0_ID = 6040099;
     public static final Version V_6_4_0 = new Version(V_6_4_0_ID, org.apache.lucene.util.Version.LUCENE_7_4_0);
     public static final int V_7_0_0_alpha1_ID = 7000001;
@@ -192,10 +192,10 @@ public static Version fromId(int id) {
                 return V_7_0_0_alpha1;
             case V_6_4_0_ID:
                 return V_6_4_0;
+            case V_6_3_1_ID:
+                return V_6_3_1;
             case V_6_3_0_ID:
                 return V_6_3_0;
-            case V_6_2_5_ID:
-                return V_6_2_5;
             case V_6_2_4_ID:
                 return V_6_2_4;
             case V_6_2_3_ID: