reactor-core/src/main/java/reactor/core/Exceptions.java
public static List<Throwable> unwrapMultiple(@Nullable Throwable potentialMultiple) {
		if (potentialMultiple == null) {
			return Collections.emptyList();
		}

		if (isMultiple(potentialMultiple)) {
			return Arrays.asList(potentialMultiple.getSuppressed());
		}

		return Collections.singletonList(potentialMultiple);
	}
public static List<Throwable> unwrapMultiple(@Nullable Throwable potentialMultiple) {
		if (potentialMultiple == null) {
			return Collections.emptyList();
		}

		if (isMultiple(potentialMultiple)) {
			return Arrays.asList(potentialMultiple.getSuppressed());
		}

		return Collections.singletonList(potentialMultiple);
	}
Attempt to unwrap a {@link Throwable} into a {@link List} of Throwables. This is
only done on the condition that said Throwable is a composite exception built by
{@link #multiple(Throwable...)}, in which case the list contains the exceptions
wrapped as suppressed exceptions in the composite. In any other case, the list
only contains the input Throwable (or is empty in case of null input).

@param potentialMultiple the {@link Throwable} to unwrap if multiple
@return a {@link List} of the exceptions suppressed by the {@link Throwable} if
multiple, or a List containing the Throwable otherwise. Null input results in an
empty List.