PP-12600: Code improvement and benchmark documentation (#1205)

src/main/java/uk/gov/pay/card/resources/CardIdResource.java

@@ -45,9 +45,9 @@ public Response cardInformation(@NotNull @Valid CardInformationRequest cardInfor
                 .build();
     }
 
-    private Optional<Long> getCardNumber(String prefix) {
+    private Optional<Long> getCardNumber(String cardNumber) {
         try {
-            return Optional.of(Long.valueOf(prefix));
+            return Optional.of(Long.valueOf(cardNumber));
         } catch (NumberFormatException e) {
             logger.info("Received card number that cannot be parsed into long");
             return Optional.empty();

src/test/java/uk/gov/pay/card/bench/RangeSetCardInformationStoreBenchmark.java

@@ -24,6 +24,18 @@
  * - Change the name of the file to load in this benchmark (in the setup()) method.
  * - You would have to replace the existing test card prefixes with some new prefixes.
  * - And then run the benchmark.
+ * 
+ * The Benchmark outputs something like the following:
+ * 
+ * Benchmark                                               (cardIdPrefix)  Mode  Cnt  Score   Error  Units
+ * RangeSetCardInformationStoreBenchmark.runBenchmark  511226661120000000  avgt   20  0.145 ± 0.001  us/op
+ * RangeSetCardInformationStoreBenchmark.runBenchmark  511226661130000000  avgt   20  0.142 ± 0.004  us/op
+ * RangeSetCardInformationStoreBenchmark.runBenchmark  511226661140000000  avgt   20  0.146 ± 0.002  us/op
+ * etc
+ * 
+ * This means the test card 511226661120000000 took 0.145 microseconds to run on average over 20 iterations.
+ * Assuming that the results are normally distributed, one would expect that the "true" execution time for 
+ * that method has a 99.9% probability to be somewhere between 0.145± 0.001 microseconds.
  */
 @State(Scope.Benchmark)
 public class RangeSetCardInformationStoreBenchmark {