Add inventory monitor module

[chimp1984]

This adds a new module containing the new inventory monitor project.
It is running since a few weeks under http://46.101.179.224/ and some of the seeds have updated to that branch already.
It is the implementation of bisq-network/projects#45
@jmacxx is working on a webapp which should finally replace the simple http server used atm.
It will still need fine tuning of the deviation alert/warning thresholds but it is already pretty useful and helps to detect seed node issues.
Most of the code is only relevant to the monitor project and seed nodes, so it carries very low risk for normal users.

[chimp1984]

@ripcurlx Please remove rule that empty catch with ignore as param name is causing warnings.

[chimp1984]

@ripcurlx Please remove rule that empty catch when using ignore is causing issues

[ripcurlx]

@ripcurlx Please remove rule that empty catch when using ignore is causing issues

Just removed the pattern.

[sqrrm]

Looks good. Some comments that don't really have to be tended to.

[sqrrm]

As always, prefer to return early instead of huge blocks.

[sqrrm]

Suggested change

	p2PDataStorage.getMapForDataResponse(getInventoryRequest.getVersion()).values().stream()
	.map(e -> e.getClass().getSimpleName())
	.forEach(className -> {
	Optional<InventoryItem> optionalEnum = Enums.getIfPresent(InventoryItem.class, className);
	if (optionalEnum.isPresent()) {
	InventoryItem key = optionalEnum.get();
	dataObjects.putIfAbsent(key, 0);
	int prev = dataObjects.get(key);
	dataObjects.put(key, prev + 1);
	}
	});
	p2PDataStorage.getMap().values().stream()
	.map(ProtectedStorageEntry::getProtectedStoragePayload)
	.filter(Objects::nonNull)
	.map(e -> e.getClass().getSimpleName())
	.forEach(className -> {
	Optional<InventoryItem> optionalEnum = Enums.getIfPresent(InventoryItem.class, className);
	if (optionalEnum.isPresent()) {
	InventoryItem key = optionalEnum.get();
	dataObjects.putIfAbsent(key, 0);
	int prev = dataObjects.get(key);
	dataObjects.put(key, prev + 1);
	}
	});
	p2PDataStorage.getMapForDataResponse(getInventoryRequest.getVersion()).values().stream()
	.map(e -> e.getClass().getSimpleName())
	.forEach(className -> addItem(dataObjects, className));
	p2PDataStorage.getMap().values().stream()
	.map(ProtectedStorageEntry::getProtectedStoragePayload)
	.filter(Objects::nonNull)
	.map(e -> e.getClass().getSimpleName())
	.forEach(className -> addItem(dataObjects, className));

With addItem()

    private void addItem(Map<InventoryItem, Integer> dataObjects, String className) {
        Optional<InventoryItem> optionalEnum = Enums.getIfPresent(InventoryItem.class, className);
        if (optionalEnum.isPresent()) {
            InventoryItem key = optionalEnum.get();
            dataObjects.putIfAbsent(key, 0);
            int prev = dataObjects.get(key);
            dataObjects.put(key, prev + 1);
        }
    }

[sqrrm]

This comment is lacking a bit when it comes to the punch line.

[sqrrm]

utACK

@chimp1984 Comments can be fixed elsewhere if you feel like it, I want to merge this.