public Builder setHeuristicCoefficient(final float heuristicCoefficient) {
            this.heuristicCoefficient = heuristicCoefficient;
            return this;
        }
Sets coefficient to be used in heuristic freshness caching. This is
interpreted as the fraction of the time between the {@code Last-Modified}
and {@code Date} headers of a cached response during which the cached
response will be considered heuristically fresh.
@param heuristicCoefficient should be between {@code 0.0} and
  {@code 1.0}.
@return this instance.
httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/CacheConfig.java