@JsonIgnore
    private static void populateGetterMap() {
        // A set of mappings from the internal stat key to the getter to get the docRefs for it.
        // Each InternalStatisticKey must have a corresponding getter in this class
        // i.e "Stream Task Queue Size" => getStreamTaskQueueSizeDocRefs()
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.BENCHMARK_CLUSTER,
                InternalStatisticsConfig::getBenchmarkClusterDocRefs);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.CPU,
                InternalStatisticsConfig::getCpuDocRefs);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.EVENTS_PER_SECOND,
                InternalStatisticsConfig::getEventsPerSecondDocRefs);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.HEAP_HISTOGRAM_BYTES,
                InternalStatisticsConfig::getHeapHistogramBytesDocRefs);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.HEAP_HISTOGRAM_INSTANCES,
                InternalStatisticsConfig::getHeapHistogramInstancesDocRefs);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.MEMORY,
                InternalStatisticsConfig::getMemoryDocRefs);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.METADATA_STREAM_SIZE,
                InternalStatisticsConfig::getMetaDataStreamSizeDocRefs);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.METADATA_STREAMS_RECEIVED,
                InternalStatisticsConfig::getMetaDataStreamsReceivedDocRefs);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.REF_DATA_STORE_ENTRY_COUNT,
                InternalStatisticsConfig::getRefDataStoreEntryCount);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.REF_DATA_STORE_SIZE,
                InternalStatisticsConfig::getRefDataStoreSize);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.REF_DATA_STORE_STREAM_COUNT,
                InternalStatisticsConfig::getRefDataStoreStreamCount);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.PIPELINE_STREAM_PROCESSOR,
                InternalStatisticsConfig::getPipelineStreamProcessorDocRefs);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.SEARCH_RESULTS_STORE_SIZE,
                InternalStatisticsConfig::getSearchResultsStoreSize);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.SEARCH_RESULTS_STORE_COUNT,
                InternalStatisticsConfig::getSearchResultsStoreCount);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.STREAM_TASK_QUEUE_SIZE,
                InternalStatisticsConfig::getStreamTaskQueueSizeDocRefs);
        KEY_TO_DOC_REFS_GETTER_MAP.put(
                InternalStatisticKey.VOLUMES,
                InternalStatisticsConfig::getVolumesDocRefs);
    }
Create a list of {@link DocRef} objects that are associated with a single {@link InternalStatisticKey}
stroom-statistics/stroom-statistics-impl/src/main/java/stroom/statistics/impl/InternalStatisticsConfig.java