@Nonnull
    public MemoryUsage getMemoryUsageAfterLastGC() {
        return memoryUsage == null ? MemoryUsage.createSnapshot() : memoryUsage;
    }
Returns the memory usage of Openfire as it was recorded directly after the last garbage collection event. When
garbage collection has not yet occurred (eg: shortly after startup), the current memory usage will be returned.

@return Memory usage statistics.
xmppserver/src/main/java/org/jivesoftware/util/MemoryUsageMonitor.java