code: public static <T> Mono<T> fromSupplier(Supplier<? extends T> supplier) {
  		return onAssembly(new MonoSupplier<>(supplier));
  	}
docs: Create a {@link Mono}, producing its value using the provided {@link Supplier}. If
  the Supplier resolves to {@code null}, the resulting Mono completes empty.
  
  <p>
  <img class="marble" src="doc-files/marbles/fromSupplier.svg" alt="">
  <p>
  @param supplier {@link Supplier} that will produce the value
  @param <T> type of the expected value
  
  @return A {@link Mono}.