add version 6.4.4

Author: javanna

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

@@ -186,6 +186,8 @@ public class Version implements Comparable<Version>, ToXContentFragment {
     public static final Version V_6_4_2 = new Version(V_6_4_2_ID, org.apache.lucene.util.Version.LUCENE_7_4_0);
     public static final int V_6_4_3_ID = 6040399;
     public static final Version V_6_4_3 = new Version(V_6_4_3_ID, org.apache.lucene.util.Version.LUCENE_7_4_0);
+    public static final int V_6_4_4_ID = 6040499;
+    public static final Version V_6_4_4 = new Version(V_6_4_4_ID, org.apache.lucene.util.Version.LUCENE_7_4_0);
     public static final int V_6_5_0_ID = 6050099;
     public static final Version V_6_5_0 = new Version(V_6_5_0_ID, org.apache.lucene.util.Version.LUCENE_7_5_0);
     public static final int V_6_6_0_ID = 6060099;
@@ -208,6 +210,8 @@ public static Version fromId(int id) {
                 return V_6_6_0;
             case V_6_5_0_ID:
                 return V_6_5_0;
+            case V_6_4_4_ID:
+                return V_6_4_4;
             case V_6_4_3_ID:
                 return V_6_4_3;
             case V_6_4_2_ID: