renamed mutationAt to hammingContributionAt and removed 'Of' from one of the test method name - as per pull-request feedback

assignments/java/hamming/example.java

         final int length = Math.min(leftStrand.length(), rightStrand.length());
         int distance = 0;
         for (int i = 0; i < length; i++) {
-          distance += mutationAt(i, leftStrand, rightStrand);
+          distance += hammingContributionAt(i, leftStrand, rightStrand);
         }
 
         return distance;
     }
 
-    private static int mutationAt(int index, String leftStrand, String rightStrand) {
+    private static int hammingContributionAt(int index, String leftStrand, String rightStrand) {
       return leftStrand.charAt(index) != rightStrand.charAt(index) ? 1 : 0;
     }
 

assignments/java/hamming/src/test/java/HammingTest.java

     }
 
     @Test
-    public void testCompleteHammingDistanceOfForSmallStrand() {
+    public void testCompleteHammingDistanceForSmallStrand() {
         assertThat(Hamming.compute("AG", "CT"), is(2)); 
     }