code: protected static Set<StreamCapability> addCapabilities(@Nullable StreamSupplier<?> supplier,
  			StreamCapability capability, StreamCapability... capabilities) {
  		EnumSet<StreamCapability> result = EnumSet.of(capability, capabilities);
  		if (supplier != null) {
  			result.addAll(supplier.getCapabilities());
  		}
  		return result;
  	}
docs: This method is useful for stream transformers that might add some capability to the stream