code: public static BulkheadMetricsCollector ofSupplier(MetricNames names, Supplier<? extends Iterable<? extends Bulkhead>> supplier) {
          return new BulkheadMetricsCollector(names, supplier);
      }
docs: Creates a new collector with custom metric names and
  using given {@code supplier} as source of bulkheads.
  
  @param names    the custom metric names
  @param supplier the supplier of bulkheads, note that supplier will be called one every {@link #collect()}