public ObjectNode getStringMember(String key, Consumer<String> consumer) {
        getStringMember(key).map(StringNode::getValue).ifPresent(consumer);
        return this;
    }
The same as {@link #expectStringMember(String, Consumer)} but the member is optional.

@param key Key to retrieve.
@param consumer Consumer that accepts the string value.
@return Returns the node.
smithy-model/src/main/java/software/amazon/smithy/model/node/ObjectNode.java