Adding logging

We should also log when there is an authentication issue. Let's add a Logger to our Handler class:

private static final Logger LOGGER = 
   Logger.getLogger(Handler.class);

Then, let's modify the block where we catch the exception:

... 
  } catch (UserNotFoundException userNotFoundException) { 
    policyEffect = PolicyStatement.Effect.DENY; 
    LOGGER.info("User authentication failed for token " +  
      authenticationToken); 
  } 
.... 

Maybe at this point, we can create another test to check whether our Handler class is returning the denial policy. We need mocking for that because we will create a mock AuthenticationInput object, and easymock and powermock are good libraries for that. Let's add it to our main build.gradle file to test dependencies:

allprojects { 
  dependencies { 
    ... 
    testCompile group: 'org.easymock...