### Question:
AwsEC2Platform extends Platform implements SshBasedExperiment<AwsEC2Container> { String getUsernameForImageId (String imageId) { final Optional<String> usernameLookup = Optional.ofNullable(getImageIdToUsernameMap().get(imageId)); usernameLookup.ifPresentOrElse(username -> log.info("Using username {} for SSH", username), () -> log.debug("Using username ec2-user for SSH")); return usernameLookup.orElse(DEFAULT_EC2_CLI_USER); } @Autowired  AwsEC2Platform(AmazonEC2 amazonEC2, ContainerManager containerManager, AwsEC2SelfAwareness awsEC2SelfAwareness); private  AwsEC2Platform(); void setFilter(@NotNull Map<String, List<String>> filter); void setGroupingTags(List<String> groupingTags); void setSSHPrivateKeys(@NotNull Map<String, String> sshPrivateKeys); Map<String, String> getImageIdToUsernameMap(); void setImageIdToUsernameMap(Map<String, String> imageIdToUsernameMap); @Override ApiStatus getApiStatus(); @JsonIgnore Collection<SubnetUtils.SubnetInfo> getRoutableCidrBlocks(); void setRoutableCidrBlocks(Collection<String> routableCidrBlocks); boolean isAddressRoutable(String privateIPAddress); @Override PlatformLevel getPlatformLevel(); @Override PlatformHealth getPlatformHealth(); @Override List<Container> generateRoster(); @Override boolean isContainerRecycled(Container container); ContainerHealth checkHealth(String instanceId); void stopInstance(String... instanceIds); void terminateInstance(String... instanceIds); void startInstance(String... instanceIds); void restartInstance(String... instanceIds); void setSecurityGroupIds(String networkInterfaceId, Collection<String> securityGroupIds); String getChaosSecurityGroupForInstance(String instanceId); boolean isContainerTerminated(String instanceId); boolean isAutoscalingGroupAtDesiredInstances(String autoScalingGroupName); boolean hasKey(String keyName); @Override void recycleContainer(AwsEC2Container container); void triggerAutoscalingUnhealthy(String instanceId); @Override String getEndpoint(AwsEC2Container container); @Override SSHCredentials getSshCredentials(AwsEC2Container container); boolean isStarted(AwsEC2Container awsEC2Container); Map<String, Set<String>> getNetworkInterfaceToSecurityGroupsMap(String instanceId); boolean verifySecurityGroupIdsOfNetworkInterfaceMap(String instanceId, Map<String, Set<String>> originalSecurityGroups);  }### Answer:
@Test public void getUsernameForImageId () { awsEC2Platform.setImageIdToUsernameMap(Map.of("rhel", "root", "amazon-linux", "ec2-user")); assertEquals("root", awsEC2Platform.getUsernameForImageId("rhel")); assertEquals("ec2-user", awsEC2Platform.getUsernameForImageId("amazon-linux")); assertEquals("ec2-user", awsEC2Platform.getUsernameForImageId("centos")); }