Method asMap_get

src/main/java/fieldbox/boxes/Box.java:871–884

(String p)

			if (calling == null) throw new Error();
			return calling.apply(this, a);
		}

		@Override
		public Object asMap_get(String p) {
			T q = from.breadthFirst(from.upwards())
				.map(x -> x.properties.get(storageProperty))
				.filter(x -> x != null)
				.filter(x -> x.containsKey(p))
				.findFirst()
				.map(x -> x.get(p))
				.orElseGet(() -> null);
			if (q != null) return q;

			return from.properties.computeIfAbsent(storageProperty, (k) -> autoconstructor.apply(from))
				.get(p);
		}