for (PropertySource source : sources) {

			@SuppressWarnings("unchecked")
			Map<String, Object> value = (Map<String, Object>) source.getSource();
			for (String key : value.keySet()) {

				if (!key.contains("[")) {

					// Not an array, add unique key to the map
					combinedMap.put(key, value.get(key));

				}
				else {

					// An existing array might have already been added to the property map
					// of an unequal size to the current array. Replace the array key in
					// the current map.
					key = key.substring(0, key.indexOf("["));
					Map<String, Object> filtered = new LinkedHashMap<>();
					for (String index : value.keySet()) {
						if (index.startsWith(key + "[")) {
							filtered.put(index, value.get(index));
						}
					}
					map.put(key, filtered);
				}
			}

		}

a[0]: 0
a[1]: 1
...
a[1000]: 1000