static ContainerTypeSignature ofIterable(String iterableTypeName, TypeSignature elementTypeSignature) {
        requireNonNull(iterableTypeName, "iterableTypeName");
        requireNonNull(elementTypeSignature, "elementTypeSignature");
        return new ContainerTypeSignature(TypeSignatureType.ITERABLE, iterableTypeName,
                                          ImmutableList.of(elementTypeSignature));
    }
Creates a new container type with the specified container type name and the type signatures of the
elements it contains.

@throws IllegalArgumentException if the specified type name is not valid or
                                 {@code elementTypeSignatures} is empty.
core/src/main/java/com/linecorp/armeria/server/docs/TypeSignature.java