Adding contributor and small change in example answer

Author: jagdish-15

exercises/practice/two-bucket/.meta/config.json

@@ -6,6 +6,7 @@
     "FridaTveit",
     "jagdish-15",
     "jmrunkle",
+    "kahgoh",
     "lemoncurry",
     "LoadingBG",
     "mirkoperillo",

exercises/practice/two-bucket/.meta/src/reference/java/TwoBucket.java

@@ -7,7 +7,7 @@ final class TwoBucket {
     private String finalBucket = "";
     private int otherBucket = Integer.MAX_VALUE;
 
-    private List<Map.Entry<Integer, Integer>> statesReached = new ArrayList<>();
+    private final List<Map.Entry<Integer, Integer>> statesReached = new ArrayList<>();
 
     TwoBucket(int bucketOneCap, int bucketTwoCap, int desiredLiters, String startBucket) {
         checkIfImpossible(desiredLiters, bucketOneCap, bucketTwoCap);