presto-main/src/main/java/io/prestosql/failuredetector/HeartbeatFailureDetector.java/HeartbeatFailureDetector/getRecentFailuresByType
class HeartbeatFailureDetector:        @JsonProperty
        public synchronized Map<String, Double> getRecentFailuresByType()
        {
            ImmutableMap.Builder<String, Double> builder = ImmutableMap.builder();
            for (Map.Entry<Class<? extends Throwable>, DecayCounter> entry : failureCountByType.entrySet()) {
                builder.put(entry.getKey().getName(), entry.getValue().getCount());
            }
            return builder.build();
        }