Helper class to build {@link MetricsSource} object from annotations.
 * <p>
 * For a given source object:
 * <ul>
 * <li>Sets the {@link Field}s annotated with {@link Metric} to
 * {@link MutableMetric} and adds it to the {@link MetricsRegistry}.</li>
 * <li>
 * For {@link Method}s annotated with {@link Metric} creates
 * {@link MutableMetric} and adds it to the {@link MetricsRegistry}.</li>
 * </ul>
Helper class to build {@link MetricsSource} object from annotations.
 * <p>
 * For a given source object:
 * <ul>
 * <li>Sets the {@link Field}s annotated with {@link Metric} to
 * {@link MutableMetric} and adds it to the {@link MetricsRegistry}.</li>
 * <li>
 * For {@link Method}s annotated with {@link Metric} creates
 * {@link MutableMetric} and adds it to the {@link MetricsRegistry}.</li>
 * </ul> | MetricsSourceBuilder.java