public <R> R call(final Supplier<R> supplier) {
            Call call = localCall.get();
            if (call == null) {
                call = currentCalls.computeIfAbsent(Thread.currentThread(), k -> new Call());
                localCall.set(call);
            }
            return call.call(supplier);
        }
Creates a non-static {@link LocalMetrics} for transient use in a class/method.

@param isEnabled If false returns an instance that does nothing apart from call
                 the passed runnables/suppliers.
stroom-util/src/main/java/stroom/util/logging/SimpleMetrics.java