Handle release of 5.6.1

* Add a version constant for 5.6.2 so that the 5.6.1 constant
represents the 5.6.1 release and the 5.6.2 constant represents
the unreleased 5.6 branch.

Author: nik9000

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

@@ -93,8 +93,11 @@ public class Version implements Comparable<Version> {
     public static final int V_5_6_0_ID = 5060099;
     public static final Version V_5_6_0 = new Version(V_5_6_0_ID, org.apache.lucene.util.Version.LUCENE_6_6_0);
     public static final int V_5_6_1_ID = 5060199;
-    // use proper Lucene constant once we are on a Lucene snapshot that knows about 6.6.1
+    // TODO use proper Lucene constant once we are on a Lucene snapshot that knows about 6.6.1
     public static final Version V_5_6_1 = new Version(V_5_6_1_ID, org.apache.lucene.util.Version.fromBits(6, 6, 1));
+    public static final int V_5_6_2_ID = 5060299;
+    // TODO use proper Lucene constant once we are on a Lucene snapshot that knows about 6.6.1
+    public static final Version V_5_6_2 = new Version(V_5_6_2_ID, org.apache.lucene.util.Version.fromBits(6, 6, 1));
     public static final int V_6_0_0_alpha1_ID = 6000001;
     public static final Version V_6_0_0_alpha1 =
             new Version(V_6_0_0_alpha1_ID, org.apache.lucene.util.Version.LUCENE_7_0_0);
@@ -135,6 +138,8 @@ public static Version fromId(int id) {
                 return V_6_0_0_alpha2;
             case V_6_0_0_alpha1_ID:
                 return V_6_0_0_alpha1;
+            case V_5_6_2_ID:
+                return V_5_6_2;
             case V_5_6_1_ID:
                 return V_5_6_1;
             case V_5_6_0_ID: