In some contexts is unclear why an autoscaling policy decides to request
more resources, i.e. if there's an unassigned shard that remains unassigned
even after adding more resources. It would be help to have more information
around the decisions taken by the deciders so it is easier to understand and
track them.
x-pack/plugin/autoscaling/src/main/java/org/elasticsearch/xpack/autoscaling/storage/ProactiveStorageDeciderService.java
this.forecasted = in.readLong();
            this.forecastWindow = in.readTimeValue();
        }
        @Override
        public String summary() {
            return reason;
        }
        public long unassigned() {
            return unassigned;
        }
        public long assigned() {
            return assigned;
        }
        public long forecasted() {
            return forecasted;
        }
        public TimeValue forecastWindow() {
            return forecastWindow;
        }
        @Override
        public String getWriteableName() {
            return NAME;
        }
        @Override
        public void writeTo(StreamOutput out) throws IOException {
            out.writeString(reason);
            out.writeLong(unassigned);
            out.writeLong(assigned);
            out.writeLong(forecasted);
            out.writeTimeValue(forecastWindow);