public static HystrixCommandMetrics getInstance(HystrixCommandKey key, HystrixCommandGroupKey commandGroup, HystrixCommandProperties properties) {
        return getInstance(key, commandGroup, null, properties);
    }
public static HystrixCommandMetrics getInstance ( HystrixCommandKey key , HystrixCommandGroupKey commandGroup , HystrixCommandProperties properties ) { return getInstance ( key , commandGroup , null , properties ) ; }
Get or create the {@link HystrixCommandMetrics} instance for a given {@link HystrixCommandKey}.
<p>
This is thread-safe and ensures only 1 {@link HystrixCommandMetrics} per {@link HystrixCommandKey}.

@param key
{@link HystrixCommandKey} of {@link HystrixCommand} instance requesting the {@link HystrixCommandMetrics}
@param commandGroup
Pass-thru to {@link HystrixCommandMetrics} instance on first time when constructed
@param properties
Pass-thru to {@link HystrixCommandMetrics} instance on first time when constructed
@return {@link HystrixCommandMetrics}