Add version 6.6.1 (elastic#37975)

Author: matriv

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

@@ -116,10 +116,10 @@ public class Version implements Comparable<Version>, ToXContentFragment {
     public static final Version V_6_5_3 = new Version(V_6_5_3_ID, org.apache.lucene.util.Version.LUCENE_7_5_0);
     public static final int V_6_5_4_ID = 6050499;
     public static final Version V_6_5_4 = new Version(V_6_5_4_ID, org.apache.lucene.util.Version.LUCENE_7_5_0);
-    public static final int V_6_5_5_ID = 6050599;
-    public static final Version V_6_5_5 = new Version(V_6_5_5_ID, org.apache.lucene.util.Version.LUCENE_7_5_0);
     public static final int V_6_6_0_ID = 6060099;
     public static final Version V_6_6_0 = new Version(V_6_6_0_ID, org.apache.lucene.util.Version.LUCENE_7_6_0);
+    public static final int V_6_6_1_ID = 6060199;
+    public static final Version V_6_6_1 = new Version(V_6_6_1_ID, org.apache.lucene.util.Version.LUCENE_7_6_0);
     public static final int V_6_7_0_ID = 6070099;
     public static final Version V_6_7_0 = new Version(V_6_7_0_ID, org.apache.lucene.util.Version.LUCENE_7_7_0);
     public static final int V_7_0_0_ID = 7000099;
@@ -142,10 +142,10 @@ public static Version fromId(int id) {
                 return V_7_0_0;
             case V_6_7_0_ID:
                 return V_6_7_0;
+            case V_6_6_1_ID:
+                return V_6_6_1;
             case V_6_6_0_ID:
                 return V_6_6_0;
-            case V_6_5_5_ID:
-                return V_6_5_5;
             case V_6_5_4_ID:
                 return V_6_5_4;
             case V_6_5_3_ID: