Add comment explaining json file name

data/beaconrestapi/src/test/java/tech/pegasys/teku/beaconrestapi/handlers/v1/beacon/PostStateValidatorBalancesTest.java

@@ -112,7 +112,7 @@ void metadata_shouldHandle200() throws IOException {
     final String data = getResponseStringFromMetadata(handler, SC_OK, responseData);
     final String expected =
         Resources.toString(
-            Resources.getResource(
+            Resources.getResource( // GET and POST have same expected response
                 GetStateValidatorBalancesTest.class, "getStateValidatorBalances.json"),
             UTF_8);
     assertThat(data).isEqualTo(expected);